This is a year later, but maybe somebody finds their way here and encounters the "Test connection failed because of an error in initializing provider. Invalid UDL file." or similar UDL error. I got this and investigated other how-to-define-SSIS-Excel articles. This one
mentioned that you must install "Microsoft Office 12.0 Access Database Engine OLE DB Provider" and gave this MS link:
When I install the MS component and follow the steps in the first link -- they are slightly different from this SQLServerCentral article -- the UDL errors go away.
If an additional download is indeed the fix, then that sucks -- MS gives us the option of picking a Connection Manager OLE DB Provider that is not loaded on the system...ugh.