I have a solution which I think ...

I have a solution which I think works (I cannot come up with a test case where it fails). However, I get the following hidden test failure:

Fail:Hidden test "You can move to all four direction (don't forget about up and left)"

I have made sure that my solution can properly find a "goal" which is North, South, West or East of the starting point. Can you further describe this error without giving away the exact test?