Why does using Shell to run a .MSI file sometimes fail in VB6?
I am attempting to launch the .NET CF installer from a VB6 app using the following code (for the sake of brevity I have replaced the full path to the installer with "(full path)"):
    
    Shell "C:\WINDOWS\system32\msiexec.exe /fa ""(full path)\NETCFSetupv35.msi"""

I've run this on four machines so far.  On two it works fine, on the other two it fails.  When it works, the CF installer just runs.  When it fails, the first thing it does is pop up a dialog saying, "The feature you are trying to use is on a CD ROM or other removable disk that is not available."  The dialog provides a text box to enter a path and a browse button to find it, so I provide the path, click the open button and get this error, "Error 1706.No valid source could be found for product Microsoft .NET Compact Framework 3.5.  The Windows Installer cannot continue."

Can anyone tell me what's going wrong here?  What is missing from the machines upon which it fails?
Why does using Shell to run a .MSI file sometimes fail in VB6?
===

I am attempting to launch the .NET CF installer from a VB6 app using the following code (for the sake of brevity I have replaced the full path to the installer with "(full path)"):
    
    Shell "C:\WINDOWS\system32\msiexec.exe /fa ""(full path)\NETCFSetupv35.msi"""

I've run this on four machines so far.  On two it works fine, on the other two it fails.  When it works, the CF installer just runs.  When it fails, the first thing it does is pop up a dialog saying, "The feature you are trying to use is on a CD ROM or other removable disk that is not available."  The dialog provides a text box to enter a path and a browse button to find it, so I provide the path, click the open button and get this error, "Error 1706.No valid source could be found for product Microsoft .NET Compact Framework 3.5.  The Windows Installer cannot continue."

Can anyone tell me what's going wrong here?  What is missing from the machines upon which it fails?