Hi,

Well it could be one of several things:

1. The smoke generator must make good contact both hot and ground. Open the loco and make certain that the little center wire is touching the metal tongue. Then remove the smoke generator and make certain that there is metal showing in the smoke stack. Sometimes paint gets in there and prevents a good contact. If there is paint scrape it until you get to the metal.

2. You have put in too much fluid and flooded the smoke generator. Clean it out and clean the center core if it is the removable type like the Marklin 7226.

3. You may have a bad smoke generator. Hook up wires to it outside of the loco. Center track studs to the little wire and rail to the body. See if it works.

Hope this helps.

Jack