Hi! Gary

I got it !, after you gave me your comment about there may be some codes in my application which caused the problem, I have examined and found that I have included a business rule which is coded similar to method calc1() in codemine tutorial, but in the tutorial they put the "RETURN THIS.Replace('var1', 'var2', m.nvalue)" in the last session of code which different from my code. I have corrected my code and evrything is OK.
Again, thank for your idea.

Panya Suwan