Without seeing the code two things come to mind.
1. If it works on "highlight execution" mode then it points to a timing issue. Do you have multiple calls to this data? Perhaps a race condition.
2. If the data is correct when run alone and incorrect when called as a sub-VI is there a data type mismatch? Are there any coercion dots or are you doing any typecasting or variant to data conversions that may not be properly formatted?
Hope this helps.
-Dave