Though a search term is maintained in Bussines configuration for credit memo and also the same search term is there in the text file still the invoice Document type is not Credit memo.
SAP Business ByDesign
In general any special character except "(" and ")" is not allowed in the search terms
If maintained it results in an invalid search pattern so by default the document type is set as Invoice.
Please remove special character in all the search terms
KBA , AP-SIP , Supplier Invoice Processing , How To