one of which was Oracle.dll which is the file the error message complains about
That's probably not the file that's causing the grief. I think the error message is telling you that dll can't be loaded because another dll can't be found.
Without knowing anything about Oracle itself, I would expect that it ships with its own dll(s), and your problem could be that the Oracle dll(s) can't be found. Make sure the location of the Oracle dll(s) is in your path.