Form field with conditions

[Dave]

I'm sorry about this ahead of time, because I accidentally posted this
to the end of a different thread, when I wasn't paying attention to
which post button i was clicking. I meant it to be a whole new thread.
Anyway here it is.

In this form there are 2 combo boxes (as well as other objects that
aren't relative to this question). One for the Track (with choices of
1 or 2) and One for Year (with choices 1,2,3,4). And then there is a
text box that cannot be edited called ModuleID. I want the Module ID
to display a number based on the two choices the user makes. For
example if the very first entry is track 1, year 1 then i want the
Moudule ID to be one. If the next entry is the same thing then i want
the Module ID to be 2. But then if the entry changes to say, Track 1
Year 2 i want the module ID to go back to 1 (because it is the first
entry of that type). I am a complete newbie with Access and VB, and
i've been learning quickly, which my job has required me to do, but
right now I am stuck. Below is an example of what i want the ModuleID
to equal based on the track and year entered.

Example

Track Year ModuleID
1 1 1
1 1 2
1 1 3
1 2 1
1 2 2
2 2 1

Thanks for your time.