What are the reasons to obtain a duplicate key error in a process flow run to a node after export

[Numberlover]

I tried to run a program that is already running fine in other pc.but while running the same process flow from my pc sas eg.i am getting errors.the main error is occured at a portion when a dataset is exported to a table.table seems blank and the end of that process flow shows an error ''duplicate key'' error.what were the reasons for such an error.

[Reeza]

Guesses based on on code or data:

The input data is not exactly the same and there is a duplicate in one of the data sets that is not accounted for in the code somewhere, given the error, likely a PROC TRANSPOSE. 

If the input data is the same, and you've used PROC IMPORT, it's possible the import truncated some data to create duplicate keys which may not have existed in the other version. PROC IMPORT guesses at types and lengths and not always correctly.