Help problem with lathe threading. Siemens 808d turning

I have owned this lathe for just over a year, and was trying to find a good PP for it. All was fine until I came to the threading cycle. I just could not get it to thread. So I went to the controller (Siemens 808d) and entered the Cycle 99 and then ran it. At 10 RPMs I could the threading tool would go to correct threading depth then rapid to the end of the cut and start the cycle again. I am new at CNC so I don't have a lot to draw on. I was threading with it about 2 month ago and it was fine. I even took the same post and ran it again and got the same results. Have any ideas?