Add calculated query field to a Userform

Hi,

Is it possible to, after creating a custom query that has a calculated field (i.e. the sum of the QtyOrdered on the SalesLine table), add that field into a grid of a new userform?

I have tried that, but only when I drag a field from the existing field list of SalesLine table the field adding works... when I try to drag that specific calculated field onto the userform Grid, it doesn't let me add it...

Is what I am trying to do not possible? And if so, If I am trying to get a sum of something, how can I show it on a userform?

Thanks in advance.