[AccessD] Reorder Level

I placed this in the Control Source of the text box - txtReorderAmt. I
get an error - "the expression in the function contains the wrong number
of arguments."

 

 

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Maybe I'm missing the point, but I believe it should be this:

 

=IIf([txtOnHand]+[txtOnOrder])<[ReorderLevel],[ReorderLevel]-([txtOnHand
])+[txtOnOrder],0)

 

=(496 + 500) < 18 ,  18 - (496 + 500) , 0

 

  so you'd get 0 in this case.