MicroStation v8 2004 silent uninstall

Sorry I need help about silent UNINSTALL

Try the following…

• Go to Registry Editor (RegEdit)

• Search for MicroStation under this folder
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\
e.g. you could find "REG_SZ:C:\WINNT\IsUninst.exe-fC:\Bentley\Microstation.isu"

• Based on what is found under the registry key, the uninstall string would be as follows.
C:\WINNT\IsUninst.exe -fC:\Bentley\Microstation.isu -y –a

Regards,
Leonard Jones

Hi
Thanks for your answer.
I had tried that, but there are three uninstall strings in registry (only one is the main). None of them works silently (well, I don't know how do it).
I've tried with params -s -sms -silent -s /s /silent /q /qb /qn...
I've tried recording the response file (installshield)...
I've tried everything but nothing works
The registry string with the main uninstaller run this:
"C:\Program Files\InstallShield Installation Information\GUID.exe" -uninstall -guid"{8BD3BFEE-79BF-40A1-A69D-97A53F216412}_0" but I don't know silent options for this.

I always have to uninstall and install silently in my company. I have do it a lot of times but this...