Have you tried displaying the excel array before the sort? That would atleast help determine where the problem is. And don't forget that readexcel2 returns a multiple dimension array.

 Code:
$Brandshop = readexcel2(@Scriptdir + '\pccs.xlsx',,-1,-1)
For $i = 0 to UBound($brandshop)
   For $j = 0 to UBound($brandshop,2)
      ? $brandshop[$i,$j]+@CRLF
   Next
   ?
Next

(untested)