SupportAssist for Business PCs won't install

Created a deployment for SupportAssist for Business PCs - the .exe version. Now I try to install it on a client. Open a CMD prompt with admin permissions and execute " \SupportAssistx64.exe" TRANSFORMS=" \SupportAssistConfig.mst" DEPLOYMENTKEY="abcdef"

It's busy for a while and then the prompt returns. The I wanted to  run the SupportAssist self-diagnosis test. And it's not there. Only some .tmp files. Hmm. In Explorer, I open C:\Program Files\Dell\SupportAssistBusinessClient to see what's there - nothing. So I ran the command a second time. In Explorer, all files and folders appear. And after a minute, the installation is rolled back, removing all those files and folders.

Checked the Windows Application log. It lists these two errors two times:

Event 2016: .NET Runtime

Toepassing: ConfigInstaller.exe
Framework-versie: v4.0.30319
Beschrijving: het proces is beëindigd als gevolg van een onverwerkte uitzondering.
Uitzonderingsinformatie: System.MissingMethodException
bij ConfigInstaller.Program.Main(System.String[])

and:

Event 1000: Application Error

Faulting application name: ConfigInstaller.exe, version: 6.0.7332.430, time stamp: 0x8ed5aa00
Faulting module name: KERNELBASE.dll, version: 10.0.19041.1566, time stamp: 0x0833f2d4
Exception code: 0xe0434352
Fault offset: 0x0000000000034f69
Faulting process id: 0x1438
Faulting application start time: 0x01d849a1a88405d9
Faulting application path: C:\Program Files\Dell\SupportAssistBusinessClient\PCD\SA\setup\ConfigInstaller.exe
Faulting module path: C:\WINDOWS\System32\KERNELBASE.dll
Report Id: bc8f60d6-056a-481c-af00-9228ab15c73f
Faulting package full name:
Faulting package-relative application ID:

Executed the cleanup-script, but that doesn't make any difference.

Looks like there's something going on with .Net, but problems with that are very hard to tackle. So any ideas?

Simon