Traxxas transmitters need Traxxas receivers. I would suggest contacting Traxxas. Their customer support is very good. They can tell you if you have receivers and transmitters that will actually communicate with each other, and how to link or bind them. In order to be legal, the transmitters must be 2.4 ghz, not the crystal controlled 27 mhz models with the long metal antenna.

On your original problem, you may have run afoul of some confusing product branding. There are two styles of 3 line handles and bellcranks, and they have different amounts of throttle control travel. The original brand has the shorter travel. It is labelled Sturdi Built and/or J-Roberts. The other brand with more travel was first sold under the G-S brand, then later the L&R brand. Ultimately it was picked up by Brodak, and labelled Brodak/ J-Roberts. Thus, there are two different and incompatible product lines both bearing the J-Roberts name.

All that being said, they only way this could be your problem is if you have an "old" handle and a "new" bellcrank. If you bought everything new from Brodak, this can't be your problem. If you bought equipment on ebay, it's a possibility. Have the local carrier guys look at your handle compared to theirs. If there's a difference, try theirs. You may need to play with line lengths, though. Try making some short temporary test lines out of some .020 or .025 music wire.

If you think you have a matched handle and bellcrank, then you either have a mis-rigged throttle linkage to the engine, mismatched line lengths, or some sort of mechanical obstruction limiting the bellcrank. Hook up your lines and handle to the airplane. Make note of the throttle movement. Disconnect the pushrod from the carb. Do you get more movement of the throttle linkage? If so, readjust the linkage. Push the throttle trigger forward, then pull the throttle line toward you. Does the throttle move more? If so, your throttle line is too long. Try a shorter line connector on the throttle line, or bigger connectors on the up and down lines. Now, pull the throttle trigger all the way back. Unhook the throttle line so it is slack. Do you get more movement? If so, then the throttle line is too short. Try a longer line connector.

I've made many sets of carrier lines, and getting all the line lengths right is quite a balancing act. I think I've only had two sets that worked properly with all the same length line connectors. Two things that I learned along the way are to always pre-stretch your lines because  they will change when a load is applied, and leave the throttle disconnected until last. If the bellcrank isn't working right, the throttle won't work right, and if the throttle isn't working right, it can keep the bellcrank from working right.

Of course, using a radio operated throttle instead means you won't have to worry about any of it.