I am posting this in the unofficial tech discussion so that anyone can reply and help the OP.
I am not an expert in RobotC and I sure many people will be able to help much better, but from what I can tell you have them configured wrong. One of them is configured properly, but the other as an IME. Make sure that both of them are configured as Sensors in RobotC.
The way you have leftEndcoder set up seems to be correct, so set up the other one in the same way.
I agree with Kevin_Team472; this issue appears to be caused with the setup of your encoders in the Motors and Sensors Setup window. If you are using Quadrature Encoders (and not the IME’s), you will want to set the encoders up in the Motors tab as Digital encoders:
You can also set them up in the Digital Sensors tab under the appropriate ports (this tab also allows you to assign the encoders specific names:
I am going to redirect the other thread, posted in the ROBOTC-specific subforum, to this one for future reference.
We have had this problem a few times. The problem is that the photo sensor in the encoder is covered in dust. If you take the back off, you can trace the wires to where the sensor is. Blow on this sensor a few times to get the dust off. Then reassemble the sensor, and it should work.