I work in a manufacturing environment.  We have several departments that each
have several lines of mfg equipment.  Each line is identified with a number,
i.e. the surface mount department has 4 lines of equipment and these lines
are called 1, 2, 3, & 4.  I am building a database application to track the
scheduled maintenance on all this equipment.  One of my tables contains a
list of all the departments and any lines associated with them.  So, when I'm
entering a new piece of equipment I can select the appropriate line to help
ID that equipment.  When we add a new line I want my code to add 1 to the
biggest number associated with that department to generate the new line
number.  This would work fine if I didn't need to add "N/A" to the list for
pieces of equipment in these departments that are not assigned to a line.  
It's the N/A that causes the error (mentioned in my first post) when I use
DMax function to find the biggest number.

Here is an example of the data in the two fields in the table.

Dept               Line
SMT                N/A
SMT                 1
SMT                 2
SMT                 3
SMT                 4
AI                    N/A
AI                     1
AI                     2
AI                     3

Please excuse my blindness.

I simply need to exclude "N/A" in the criteria