VBscript CA returns 3

[Jiropole]

Hopefully someone can help this newbie with a simple question. I am
writing a custom action in VBscript to see if a program is running, and
pop a message box if it is. The problem is, I can't get the simplest
script to return an error -- error 3 is always returned, nomatter what
the function returns. For instance, my .vbs file (externally linked
from the CA) contains nothing but:

Function CheckRunningOutlook()
CheckRunningOutlook = 0;
End Function

My CA is supposed to call this function, and not ignore the exit code.
This is in InstallShield Express 11, built in Windows2K SP4. When the
CA happens, the install ends with a message that the process was
interrupted. What am I'm doing wrong? -- I'm a VB newbie too.

Thanks! -- Jesse

Here's the pertinent result of this CA from the setup log:

MSI (c) (00:7C) [11:45:11:487]: Doing action: check_running_outlook
Action 11:45:11: check_running_outlook.
Action start 11:45:11: check_running_outlook.
MSI (c) (00:F4) [11:45:11:487]: Cloaking enabled.
MSI (c) (00:F4) [11:45:11:487]: Attempting to enable all disabled
priveleges before calling Install on Server
MSI (c) (00:F4) [11:45:11:487]: Connected to service for CA interface.
MSI (c) (00:A4) [11:45:11:537]: Entering
MsiProvideComponentFromDescriptor. Descriptor:
GfXmE~Yz*@5HHM+Pw4D]AlwaysInstall>M5KDYSUnf(HA*L[xeX)y, PathBuf:
17DEB9C, pcchPathBuf: 17DEDAC, pcchArgsOffset: 17DEB68
MSI (c) (00:A4) [11:45:11:537]: MsiProvideComponentFromDescriptor
called for component {997FA962-E067-11D1-9396-00A0C90F27F9}: returning
harcoded oleaut32.dll value
MSI (c) (00:A4) [11:45:11:537]: MsiProvideComponentFromDescriptor is
returning: 0
Action ended 11:45:11: check_running_outlook. Return value 3.
DEBUG: Error 2896: Executing action check_running_outlook failed.
Internal Error 2896. check_running_outlook
Action ended 11:45:11: InstallWelcome. Return value 3.