MS-Access Data Type mismatch in Criteria Expression

Question

I created a working Union within a query.

SELECT tblGlass.Address, tblGlass.Quantity, tblGlass.Width, tblGlass.Height, 
tblGlass.Thickness, tblGlass.Finish
FROM tblGlass
WHERE tblGlass.Ordered=No;


UNION SELECT tblSeansGlass.Address, tblSeansGlass.Quantity, 
tblSeansGlass.Width, tblSeansGlass.Height, tblSeansGlass.Thickness, 
tblSeansGlass.Finish
FROM tblSeansGlass
WHERE tblSeansGlass.Ordered=No;

I would now like to add a module to both tables which works out a price:

GlassPrice([Width],[Height],[Thickness],[Quantity],[Finish]) AS [Glass Price]

So the final code looks like this:

SELECT tblGlass.Address, tblGlass.Quantity, tblGlass.Width, tblGlass.Height, 
tblGlass.Thickness, tblGlass.Finish, GlassPrice([Width],[Height],
[Thickness],[Quantity],[Finish]) AS [Glass Price]
FROM tblGlass
WHERE tblGlass.Ordered=No;


UNION SELECT tblSeansGlass.Address, tblSeansGlass.Quantity, 
tblSeansGlass.Width, tblSeansGlass.Height, tblSeansGlass.Thickness, 
tblSeansGlass.Finish, GlassPrice([Width],[Height],[Thickness],[Quantity],
[Finish]) AS [Glass Price]
FROM tblSeansGlass
WHERE tblSeansGlass.Ordered=No;

However, I get an error:

"Data type mismatch in criteria expression."

Answer 1

Thanks to Andre's comment I found the source of the problem to be a half filled entry in tblSeansGlass. Deleting this entry solved the problem. Thanks again Andre!