Compare same campaign - Different dates in Previous Year Using DAX

Edited: Got it working. added Convert ((...), String)

So far have the following code, but it's not working when i insert -1 it no longer works.
Tried adding "Value" - doesn't help




I'm close - also it's direct query in dual mode so no calculated column is allowed

Var last_campaign = (LEFT(SELECTEDVALUE(Date[Campagin_Name]),3)&" "& Value(RIGHT(SELECTEDVALUE(Date[Campagin_Name]),4)-1))

return

CALCULATE([Sales],
REMOVEFILTERS(Date),
Filter(Date,Values(Date[Campagin_Name])=last_campaign))