The application requires MS Excel as an pre-requisite.
When machine has MSoffice installed already on it, setup.exe installs cExcel.xla file under C:\Program Files\Microsoft Office\OFFICE11\XLSTART and on MS Excel 2007 the setup.exe installs cExcel.xla file under C:\Program Files\Microsoft Office\Office12\XLSTART
To make the application install the .xla file accrodingle depending upon the Office version, implemnted a System Search, created two components with the same file pointing to the destinaltion say (cExcel.xla pointing to C:\Program Files\Microsoft Office\Office12\ and cExcel.xla to C:\Program Files\Microsoft Office\Office11\)then conditionalise those components with the property used in System search.
Second issues i came across is that the size of the file SOX-XL.dll when installled on Excel 2003 differs when compared after installing it on Excel 2007.
So Created separate components for the same file , conditionalising them depending upon the version of Excel (2003/2007)(same property used for which system search was defined)
Also found out for the file SOX-XL.dll, progid points to diferrent CLSID and only one typelib data entry is loaded whereas on Excel 2003 Progid points to some diferrent CLSID.
So I extracted the COM information for the dll file separately on Excel 2003 and 2007 and added them through registry.Contionalising the component again.
The addin SOX-XL appears only on Excel 2007 and not on Excel 2003.
Ensure that the COM information is properly populated and the correct file is installed on the Ms office version inorder to make the add-in work properly.