Field "Contract Balance" cannot accept the provided value: Could not parse number

Hi Folks,

I’m having a problem with an automation that I built. Initially it worked but now it doesn’t. Essentially what I’m trying to do is this:

  1. the trigger is a new record creation in 'Table C"
  2. Then we work to update a field in “Table B” using the linked id of a lookup field from 'Table C". Then in the field area I simply try to create a simple subtraction formula: Current balance - amount

But I keep getting this error! (screenshot attached) Any idea what could be happening?