EDI Shipto Failures

We are having a problem with EDI failures due to an invalid shipto being chosen by the Requestor for the vendor on the PO. I am unsure if it is due to us using a wrong set-up or if it is how Lawson is designed to be used. We spend a large amount of time every day on these.

We do just-in-time delivery with our med/surg distributors and desktop delivery with our office supply and janitorial vendors. Therefore, Requestors may have several shipto's they use:

1) Receiving Dock - this is the shipto for most vendors
2) Requesting location - this is used for the just-in-time deliveries; they may have several since one Requestor may order for multiple units. We send the Requesting location in the SDQ03 field thru EDI.
3) Departments - this is for desktop delivery; they may have several since one Requestor may order for multiple units

All of our issues are from #1 and #3, we constantly re-educate the end users on this, but for some reason they still find this confusing. Honestly, I found it confusing when I first started since my last system autopopulated that information for me based on vendor; of course, we also had on Requestor per location which does not work here.

Does anyone else have these issues? How is everyone else setup?

Thanks,

Rebecca