John and Mary filed their separate returns in VA and MD respectively, and each of their returns has errors, they want to correct the errors and file jointly.

There is no problem in VA as they can file combined returns. For MD, they need to file nonresident return per MD instruction when one of spouses is a nonresident. The return was rejected with the following message. 



What is the defect that it refers to? The proconnect software, or the MD state's software? I think the reason is John has never filed the original return, so for him it is not an amendment, but he cannot file an original return because Mary has filed her return. Do should I do in this case? Thanks.