Some of my strategies have the "Object reference not set to an instance of an object" problem while running. But I can still view the performance result after run. It seems that it does not cause me too much trouble.

However, while I was trying to optimize these strategies, the performance data was not listed because of this error.

I looked through page http://www2.wealth-lab.com/WL5Wiki/kbErrorsStrategy.ashx, but didnt find much clues.
This page told me that the possible reasons are 1) some non-existed symbols or benchmark symbols, 2) some variables are not initialized. However, I checked the code carefully, no clues found. Any ideas to identify this problem?

Finally I found the problem. It is indeed caused by a null object. Thanks!