Maybe try to specify the G55 before and after the G68 line. I would not think that this is a parameter issue but I could be wrong. My first guess on why the G54 works ok is becasue this is usually your default work coordinate. I would probably look at were you are making G55 modal and were G68 is going modal. I am pretty sure that I have used G68 with different work coordinates before and never had any problems. It was a long time ago but I will see if I can track down one of my programs and take a look at the sequence of code to see how I put it.