This error message indicates that the VBScript engine is not currently registered on the machine where the install/uninstall is taking place.
The VBScript engine can be quickly registered by following these steps:
1. Run Command Prompt as administrator
1.1 Start Menu -> All Programs -> Accessories
1.2 Right click on Command Prompt and select Run as administrator
2. If you are using 32-bit version of Windows:
Type cd %windir%\system32 into the Command Prompt and hit Enter
If you are using 64-bit version of Windows:
Type cd %windir%\syswow64 into the Command Prompt and hit Enter
3. Type regsvr32 vbscript.dll into the Command Prompt and hit Enter
I didn’t find a Microsoft blog that describes this, but you can also see a description here
If you still have problems, maybe you can send an installation log to Altova Support
Such a log file can be made by executing:
MobileTogetherDesigner.exe /L*xv! <log_file_name>
BTW: Current MobileTogether version is 2.2 - also see What’s New in MobileTogether 2.2?
Altova MobileTogether Experts