dscopa,

Sorry that you are having difficulty with the Maryland 511 product.  I am unable to replicate the error message you are receiving at this time for a fiscal year filer using line 3a for separate accounting. 

It sounds like the error is on page 4, line 1g in the other income section.  Can you review and make sure you do not have any stray entries in those fields?  For example a stray "space" entered  into the description will trigger an error message.  See screenshot attached showing this scenario.  

Let me know if you were able to resolve your issue. We can message privately to work thru a resolution if you were unable get the help you needed.