How do I use validation rules to only allow one input in multiple cells?

Ive been having a little issue with this spread sheet.

The problem ive got is I cant get the validation to work where it only allows one yes in a bunch of cells and gives an error message, heres an example of what im talking about.

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Thanks in advance for a solution :D

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also, posting an actual spreadsheet showing the problem might be better for better assistance.

Uncheck "Ignore Blanks", select your data range (I assumed C2:J12) and go to Data Validation>Custom and enter this formula

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Only 1 "Yes" can be entered per row. Is that what you are looking for?