Hi Menakshi ,
I can see that you are talking about the Inbound Idoc not successfully posted right ?
As the message say that you are not using the appropriate characteristic value please find a possible entry for that field and try to reprocess in WE19 with the new value.
If still you face the same issue you can find the reason for the failure in Application Log for that Idoc .
to see that application logs , click on the TOP most status record of the IDOC and once you are in next detailed screen click on the Application Log button which will show you the clear and exact reason why your IDOC is getting failed or unable to post .