Cannot create invoices or credit notes linked to other documents

Hi,

We upgrades to 9.3 PL11 a couple of weeks ago and since then we cannot create invoices if they are linked to other documents using 'copy to' or 'copy from'. We can still create them if we use the document generation wizard.

We also cannot cancel credit notes for the same reason. We get the below error in the system message log for both issues:

In "Method" ValidateDocumentProtocolCodes and "Phase" 5, error Entered value is not valid. (Core -224) X occurred. Contact technical support.

I have reported it to our support partner but wondered if anyone my have an idea of what the problem is

Thanks