I am shooting clear butyerate dope 20% dope 10% retarder and 70% thinner,using an HVLP gun, the pressure at the gun is 15-20 LBS.
  The clear dope is "lifting & crazing"over the colors.  I mixed auto colors in the dope and using the same brand of dope and thinner this is happening. I have used these colors in dope on other models and didn't have this problem.
  If you have any suggestions please help...
              Thanks and best regards, Gil

This is what happens when you play chemist.

Try putting the first two or three coats of clear on very light... like over spray and let them dry 15-20 minutes between coats. The thinner seems high to me, could be acting  like a paint stripper. Very discouraging, to be ready for clear and have a problem. Post pictures.