My access method is simple right now just for testing:
Method Access:

paramters ItemNumber
this.price=ItemNumber+1
return this.price


On a buttons Valid I have this code.

replace system_price with thisform.price(order_guide.item_num)

^^^^ this is the line that causes the error. I eve tried:
real_price=thisform.price(order_guide.item_num)

same problem.

thanks
David