Fees as an Expense in Tessitura

Hi everyone:

I've spent a good deal of time back and forth with the good folks at Tessitura trying to find a solution for posting a fee (sales commission from a third party vendor) in Tessitura and I'm still on the hunt for the solution.

Do any of you know of a way to pay off tickets with a check received and include a fee as an expense - not revenue? User defined fee does not allow for a negative number, nor does a special price type, etc.

Example

Total tickets sold - $2,500.00

Sales fee: - 112.00

Total check: $2,388.00

Not clear what I'm missing on this but thus far, none of the proposed suggestions are working.  Thanks for any ideas / assistance!