Conditional Formating with ActiveX Controls

Good Morning. Here is what I am looking to do, I hope someone can help me!: I have a workbook with multiple sheets. I want to add conditional formatting for a cell on 1 worksheet based on if multiple ActiveX controls are checked (checkboxes) on another sheet. I have 10 checkboxes (now Linked Cells "G1" - "G10") on worksheet "Data Entry". The formula should be if all 10 boxes are checked on the "Data Entry" worksheet, cell "A1" on the "Milestone" will be gray. Any clues on how to write the formula for this Conditional Format? Thank you.

Link the checkboxes to a contiguous range of cells, say L1:L10, and then use a formula of

=COUNTIF($L$1:$L$10,TRUE)=10

in your CF