64 bit Autocad 2011 and 32 bit excel in a VBA app

I am running 64 bit AutoCAD on a windows 7 machine. An old VBA program was making use of MS excel. On this platform however, the app fails. It gives an automation error, Library not registered. The run-time error is '-2147319779(8002801d)':. The actual line it fails on is:

Set xlApp = CreateObject("Excel.Application")

Any help would br greatly appreciated.

Thanks,

Karl