TN missing transactions.


We are using webMethods 7.1.2 env. with TN,IS & Developer.

We have a situation when a partner send an EDI document(15-20 transactions) at a time,these documents are picked up by our receive service and sent to an application for processing .But since the service picks up the files at the same time, by the time the service writes it to the other application’s folder for it to process it further, there are following things happening:
1> If both the files are of same size: We get a document missing error.
2> If both the documents are not of the same size:The file written to the folder where the application needs to further process , has 2 parts appended.
i. the smaller file is written and after a new line the other file (not from start,from middle) is appended to it.
Then the TN writes an error “File format exception”.

We are trying to find out a way by which the files are written at different time period to the application.

Any help from the members is highly appreciated.

Thanks in advance.