Hello,

I have a query with calculates production for a machine in terms of
tonnes/hr.  A use will input the starting engine hours, starting
tonnes, ending engine hours, and ending tonnes for each day.  I have
an expression in a query which will subtract the starting and ending
hours/tonnes and then divide by one another.  This works great unless
maintenance was being done on the machine and no production was
acheived.  You then get 0/0 which produces the #Error message.  I
posted this question once and someone told be to write this for my
expression:

Expr1: IIf(IsError(([TonneEnd]-[TonneStart])/([EngineEnd]-
[EngineStart])),0,([TonneEnd]-[TonneStart])/([EngineEnd]-
[EngineStart]))

However, I still get the #Error message.  Is there something else I
should switch or should I somehow change the message.  I would like it
to display zero if there is no production.

Thanks in advance,

John