Why you cannot post document directly when change parked document from FBL1N ?
When you select a parked document and click on the change document button in T-code: FBL1N, the POST button is disappeared from the screen of parked document(T-code: FV60), and the post option is disabled in the document menu list.
This scenario only happen for following releases
470 From SAPKH47028
500 All Release
600 All Release
Reproducing the Issue
Execute T-code: FBL1N;
Select a parked document and click on Change Document button;
You cannot see the POST button from the screen(T-code: FV60), also post option is disabled in the Document Menu list;
However when goto T-code: FV60 transaction screen directly, POST button is seen.
This is a change in functionality by SAP note 988188.
You have Enjoy (i.e. T-code: FV60 for instance) parked documents. When you call them from FBL1N, you can change document by FBV2, but you can not post from the change mode. You have to use T-code: FBV0 instead. This standardizes the same post process like “traditionally” (i.e. T-code: FB01/FBV1) parked documents.
Use T-code: FBV0 to post document.
For more information, please check following SAP KBAs,