Unpredicted servo movement

I tested the write instinct and the nybble scotch and calibrated all the servo's. this was all successful.

But when using the communication protocol I can only sent one command e.g. sit and nybble will sit. after this commands no new commands are accepted. Tis behaviour is the same with the IR unit. Sometimes the servos rotate to unexpected positions and block the joints.

However the "m" command does fuction as it should for all servo's. The command "h" and "j: also do not work.

I reloaded the software and recalibrated the servos and mpu both the fault stayed the same.

Please HELP.