TestComplete form best practices in a DDT Data Driven Loop

To all. 

Is there a TestComplete document that shows the best practices to follow when trying to DDT from an excel spreadsheet into a web based form with dropdown fields?  I am seeing a high failure rate when trying to DDT in a data loop.  Yes, I have made sure all operations are indented that need to be a part of the loop.  Yes, I have added delays before and after the problem dropdown box in question.  Thank you in advance for your help and guidance.

-todd2