Ok, have a workaround that actually works, but would really like to get it right.
This gets the job done, but. . .
Range("x2").Formula = "=RIGHT(CELL(""filename"",R1C1),LEN(CELL(""filename"",R1C1))-FIND(""]"",CELL(""filename"",R1C1)))"
tabnames(ai) = Range("x2").Value
It's using a 1000...