Why does my code work fine on my machine but not on DoSelect?

Why does my code work fine on my machine but not on DoSelect?

       If a lot of people have already solved a challenge, the odds are that the issue is in your code.          
      There could be a couple of reasons for this:

• Your code doesn't match the expected output. The output produced by your code must exactly match the output expected by the test case, so something like a spelling error in your output will cause you to fail the challenge.
• Your code's behavior is unpredictable. If you're using C/C++, double-check for uninitialized variables or invalid memory accesses, as they can cause unpredictable behavior. If you overrun an array or attempt to print the contents of an array cell that was never initialized, your output may look like it's correct but you'll fail the question (invisible garbage characters are the worst, we know).
• If you're really convinced that there is an issue with a test case, contact us directly with specific information about the test name and test case. Be sure to specifically state why you think it's not correct!