Name Workspace output File like the RasterTIler output tile number.

I tiled a raster image with the RasterTiler and get as result 4 tiles and now I want to name the workspace output file like the output tile numbers.

Like this:

up left tile= 1 -> Filename_1.TIF

up right tile=2 ->Filename_2.TIF

bottom left tile=3 -> Filename_3.TIF

bottom right tile= 4 -> Filename_4.TIF

So I used the stringconcetonator to name the attributes like the tile numbers, but I dont get the desired result what am I doing wrong? Best Wishes Tina