Configuration Help for Cross-Connection Query with Oracle

I could really use some help with this cross query connection stuff.  I am about at my wit's end with it.  It *seems* like it should be simple enough (at least by way of all the information and tutorials I can seem to find), but it is an absolute nightmare!  The best I can get, in terms of incessant errors, is the following:

"An Oracle Client and ODBC driver are required for cross-connection queries.  Toad is unable to find the OBDC driver.  Please install missing client files, or choose the driver/Oracle home you want to use from the Advanced tab in the Connection Properties window."

I am using TDP 4.3.0.718.  This error pops up any time I create a cross-connection query builder and populate it with any data from my Oracle connection (I do not actually need to have any other data sources present).  I am not a DBA or some programming wizard, just a lowly finance user trying to make his way in the world.... I installed Oracle Client... I installed ODBC driver....  I tried EVERY SINGLE "driver/Oracle home" from the Advanced tab....  please.... help..... I'm beginning to think that this cross-connection thing is just some evil joke, and I'm clearly the punchline.