It may be a tag on flight of some European airline but they may not have fifth freedom rights on that route, thus no ticket sale would be allowed for CR-DR leg.
Condor for example flies Jamaica - DR one time for week but they apparently have no fifth freedom rights because you cannot buy ticket Jamaica - Punta Cana. I don't think problem is on the DR sides because DR grants freedom rights to anyone who asks for them, even the seventh freedom, I believe Iberojet from Spain will start operating flights from DR to other countries with aircraft based in the DR. So the problem in the case mentioned above, is most likely Jamaica does not allow it, as in case of fifth freedom rights both countries involved must grant that right.
Can you explain fifth freedom? I've never heard that term before.
1st freedom - Spanish airline flying from Madrid to Punta Cana overflying Portugal
2nd freedom - Spanish airline flying from Madrid to China with a technical stopover (refuel) in Dubai
3rd freedom - Spanish airline flying paying passengers from Madrid to Punta Cana
4th freedom - Spanish airline flying paying passengers from Santo Domingo to Madrid
5th freedom - Spanish airline flying from Madrid to Punta Cana and the flight continues onward to Costa Rica and flies local passengers originating in Punta Cana to Costa Rica or vice versa
6th freedom - Spanish airline flying passengers originating from Punta Cana to Madrid and then onward to Germany
7th freedom - Spanish airline flying from Santo Domingo to Miami, Bogota, Caracas, etc with aircraft based in Santo Domingo
8th freedom - Spanish airline flying from Madrid to Punta Cana and onward to Santo Domingo, and taking local passengers on Punta Cana to Santo Domingo leg.
9th freedom - currently used in EU - an Irish airline (Ryanair for example) flying from Vienna to Madrid.
Those are the nine freedoms of the air.