Sort column with switch

Hello,
I have created a group with different groupings based on weight. When I try to sort the new groups I have created on the basic weight column, I get an error that says: We cant sort the weightgroups by weight. There cant be more than one value in weight for the same value in weightgroups. Please choose a different column for sorting or update the data in weights.

So i created a sort by column with a switch, like this: 
SortColumn =

SWITCH([Category],
"Category A", 1,
"Category B", 2,
"Category C", 3, 0)

BUT, when i try to sort by this "sortcolumn" i get this error: A cirular dependency was detected.

Anyone knows what i should do?