By default, the Windows wim file has many indexes. Index 6 is currently set to Pro. This can change occasionally, depending on how Microsoft positions the versions. It has remained stable however, for several versions, but it can change with any new build released. Fortunately, this is an easy thing to check using DISM. Simply open the command prompt and run the following command

DISM /Get-WimInfo /WimFile:"C:\TMP\Install.wim"

In this example, the image is saved to c:\tmp but you could have the image anywhere you like.

I suspect that you might have a custom image with only one index as the result of capturing an image. In this case, the image will not contain any index except for 1. If this is the case, we need to modify the wininstall.cmd script to accommodate a custom image. This is not difficult, and we can add another menu selection, for example menu selection 4 for custom image and then the code would simply apply the image index 1.