Run LSMW for Batch input program RM07MMBL (Goods Movement) in test mode ?

Hi experts,

I am trying to use LSMW method for loading initial stock into SAP , using an extract file from legacy system. Can I do a test run using the source file in LSMW to see the fallouts before the actual processing of the data? I see a Test Data indicator in Create Batch Input session step of the LSMW, but when I check that, the system gives me an error "No entries in sequential file" . Am I missing something here, do I have to specify something in the Assign Files step if it's a test data ? or Is there some other way to run the LSMW for Inventory load in test mode?

Thanks in advance for your time.Any help is appreciated.

Thanks

Kris T