Question about assignment fees

[Bryan Barry]

I recently downloaded a template for an assignment contract, just to get an idea of one. In the assignment fee clause, it states that "this agreement is null and void if funds are not received within 48 hours of the time both parties have signed". Does this mean the buyer has to write me a check on the spot? I thought that my assignment fee comes from the title company on the day of closing? Should I remove this part from the assignment fee clause?