Goal Seek Question

Hi all, this might seem like a basic goal seek question for some of ya'll, but I am just stumped here.

With 10% vacancy which translates to $116,000, I am getting a 1.37 DSCR. I want to see how much vacancy the property can support with a 1.00 DSCR

With goal seek, I set cell at the 1.37 DSCR cell , for "to value", I hard coded 1.0, but for "by changing cell " if I put it as the the 10% vacancy cell or the 116,000 cell, it says "needs to be a value", so it has to be hard coded? I am not able to figure this one out, really appreciate any help!!! Thank you!