This may happen if the transactions were posted before the solicitation interactions were created. The Direct Marketing Response Report looks at transactions primarily, while the Response Report looks at the source analysis info from the interactions and the response info on them applied to them (if there's no SAC for any of the interactions for a source or no interactions for that source at all, it will just use the summary info on the source). The response info is added to an interaction when a transaction with the same source as the solicitation interaction is posted. If the interaction isn't created yet, there's nothing for it to update. There is nothing in TA that will update an interaction with response info after the fact.
To get the interactions and SAC updated with response info, contact TA support.