SRM PO not created from SC - Error in Transmission

Hi.

I am new to SRM so I apologise up front.

Once a shopping cart has had it's second approval it is approved but does not create the Purchase Order.

Viewing the SC in the Shopping Cart Monitor the SC has a status of Approved but has a message of "S& 150 Updating could not be completed". The Item Description status is "Error in transmission".

Looking at the workflows I can see that the SC approval workflow has completed but nothing after that.

I had a look at RZ20 but there didn't seem to be any errors. I didn't check the entire tree so I might have missed it. Are there certain things that I should check in RZ20?

I am happy to debug it but I don't where to put the breakpoint. Do you have any suggestions?

Are there any places that I can check for errors?

What creates the PO? I thought it was a workflow but i'm not so sure anymore. Is it possibly a batch job?

We are running SRM 713.

My apologies for all the questions. Please ignore the silly ones and answer the useful one.

Many thanks.

Stuart.