Modules & VBA :: How To Increment Field On A Continuous Form

I have a form that is being used for sample submission. Ideally, the user will be able to put in some information (3 or 4 fields) and the number of samples that they're taking, click the arrow and it will insert that number of samples into a temporary table that is then displayed on a continuous form. From there, they can edit samples, add more samples, and generate a report to submit to the genotyping group. Once their sample list is final, I will append it to the master list and clear the temporary table.

I've got the basics working. A looped "INSERT INTO" using a counter inserts the relevant information. I cannot, however, seem to get the numbering field to work.

Ultimately, the numbers need to look something like MySample-001, where MySample would be one of the other fields. Incrementing the 001 is the problem. In another situation in the database, I can successfully use DMax+1 to assign a single number on a single form, but I can't get it to increment the sample numbers.

Ideally, I'd like it to happen when the form is generated. However, I'm also open to having them assigned when the sample list is finalized, before inserting into master table.