If you’ve been an investor for a while, you’ve probably experienced times where your investment strategy didn’t seem to work like you thought it would. Maybe your strategy didn’t perform as well as the Dow Jones Industrial Average or S&P 500 Index, or maybe you simply unperformed your neighbor’s portfolio. Were you able to understand exactly why it didn’t work? Whatever the situation, you want answers.

Here are five reasons why your investment strategy may not have performed like you thought it would.

1. Your internal expenses were too high. One of the biggest detractors of performance is high fees, which could come in the form of mutual fund fees. When speaking about mutual fund fees, many people are unaware of the internal expenses of the funds because the fees are “invisible,” meaning there is typically no line item on your statement that shows what your mutual fund fees were in a given period.

However, mutual fund fees are certainly there. They are deducted from the performance of your fund, which is money that could have been yours. Mutual funds that have higher expense ratios tend to be those that trade more actively, or more often. On the other hand, index funds are typically some of the lowest-cost funds out there. It’s possible that a fund with higher fees might have a good track record of outperforming the index, but it’s also possible that you may have paid a higher fee for an equal or lower rate of return.

However, not all fees are bad. By paying mutual fund fees, it allows you to gain broad diversification without requiring a large portfolio size. The key takeaway here: Be sure to do your best to limit the fees you pay, and this should help your long-term performance.

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2. You exhibited poor behavior. It may be a tough pill to swallow but, in some cases, you may have been a main factor in your own underperformance by exhibiting poor investment behavior. What is poor investment behavior? It’s when you do the opposite of the old phrase “buy low, sell high” and you “buy high, sell low.”

Truthfully, it may have happened because you were trying to correctly time the market. In doing so, maybe you spent some time invested and some time on the sidelines. While your intentions were good, you likely missed some of the big positive days and, inevitably, you sold after experiencing some big down days.

Here’s the thing about market timing: Nobody has a crystal ball. Even the most intelligent minds in the world have not found a way to consistently time the market successfully and for extended periods of time. It’s incredibly difficult, if not impossible, to do. Yet, investors continue to try to do so at the cost of their own portfolios.

3. You didn’t compare apples to apples. In my view, one of the most common reasons that investors do not realize the rate of return they were expecting is because they are not evaluating their portfolios correctly. For example, let’s imagine an investor named Bob, who has a balanced and diversified portfolio built of 60 percent stocks, 40 percent bonds. Let’s also assume that the stock and bond portions of the portfolio are built using mutual funds, which hold hundreds or thousands of individual securities.

However, Bob tends to closely monitor and watch the Dow. And he is perplexed when it rises by over 300 points in a day and his portfolio barely moves. Or, Bob might cite something like the Dow being up by 10 percent over the last 12 months, but his portfolio was only up 6 percent (hypothetically).

In this case, Bob is comparing his portfolio, made up of only 60 percent stocks, to the Dow, which is made up of 100 percent stocks. Bob doesn’t realize that his portfolio is broadly diversified in stocks representing all parts of the world, while the Dow is made up of only 30 U.S. stocks. Had Bob’s portfolio been invested in 100 percent U.S. stocks, his comparison to the Dow would be more accurate. But with a 60/40 mix, he’s just not comparing apples to apples. If you feel your investment strategy didn’t work, it’s possible you’ve unknowingly made a similar faux pas.

4. Your expectations were unrealistic. Let’s look at another example of a common error in evaluation and again consider our friend Bob. Bob’s risk tolerance allows for a maximum stock allocation of 60 percent, meaning that 40 percent of his portfolio is invested in bonds. Bob feels okay about that because he has reviewed decades of performance research and has seen how well 60/40 portfolios have done. He expects to see similar returns over the next few decades.

However, Bob has failed to consider the current market environment, namely interest rates, and how the interest rate environment is different than it was for the last 30 to 40 years. From the early 1980s until about 2016, interest rates experienced a long-term, decreasing trend. The long-term fall in interest rates had a positive effect on bond prices and performance, causing bond returns to be favorable over that time period.

However, given today’s low interest rates, it’s difficult to see how similar returns could even be possible when using the same bond strategy that worked well for that last 35 years. In this case, Bob is expecting the past to repeat itself without understanding what generated those past returns. Because of that, his expectations are just unrealistic.

5. You didn’t give it enough time. Okay, so you’ve kept expenses low, you haven’t tried to time the market, you’ve been comparing apples to apples and you’ve tempered your expectations. But it still doesn’t look like your investment strategy has worked. The final evaluation miscue that can occur is that investors simply do not give their investments enough time to “work.” We live in a world of immediate gratification and short-term expectations.

However, that just doesn’t work when you’re evaluating your investment into a stock or series of stocks or funds. Investing successfully in the stock market takes time — and lots of it. Looking at a strategy’s results after only three months, 12 months or even a couple of years may not give you enough data to evaluate whether or not it’s a good long-term approach.

Although it’s difficult, you need to ask yourself: “What is truly a fair amount of time to evaluate the performance in this strategy?” Then, make a decision to be disciplined and stick to the plan for that period of time before considering any major changes.

You should consistently evaluate your portfolio and the process for making your investment decisions. It’s also important to apply prudent investment principles during this process.

Sometimes things will turn out better than you anticipated. Other times you may have to stick it out during a recession. Ultimately, be sure you are evaluating your investments properly so that you truly know if your strategy has worked or failed.

(Editor’s Note: This column originally appeared on Investopedia.com.)

— By Joe Allaria, partner at CarsonAllaria Wealth Management