Q from Excel novice

1. I created an Excel Addin (myUDF.xla) that contains my user defined
functions
and saved it in the "...Application Data\Microsoft\Excel\XLSTART"
folder so that it is automatically loaded everytime I launch Excel.

2. I then launched Excel. (it opens Book1.xls)

3. I click the "Paste Function fx" function and browse to see what User
defined functions are available.
The functions the I added in myUDF.xla show up on the list. Great...

However, when I launch Excel through automation, and then open a workbook,
and repeat step 3
my user defined functions are no longer on the list.

Please note: My addin"myUDF" is never listed in the Add-ins available even
in 2 when I launch Excel directly without automation. However, the functions
are made available in this case.

Has anyone encountered this problem when invoking Excel through automation?
How can I resolve this? Your help is greatly appreciated.

Thanks,
Siva

================
Here is a sample VB code that I used to test this:
Public Function DoLaunch(objExcelApplication As Excel.Application) As Boolean
On Local Error GoTo DoLaunchEH
Set objExcelApplication = CreateObject(mcsExcelApplication)
With objExcelApplication
.Visible = True
'.AddIns
End With
DoLaunch = True
DoLaunchEH:
End Function