Validata Lists using offset, match and counta formulas - Different Sheets

Good day all, can anyone tell me why I cannot get the below formula to work using the worksheet names? I was able to get this to work when all the data was on one sheet.

The source worksheet is called UsersRegistered (I tried =UsersRegistered! on the data validation screen)
The data list worksheet is called Lists

This is the formula:

=OFFSET($E$1,1,MATCH($A$2,$E$1:$G$1,0)-1,COUNTA(OFFSET($E$1,1,MATCH($A2,$E$1:$G$1,0)-1,11,1)),1)