I have windows 10, Oracle 12c, and Office 365 installed on my machine. When I try to connect to an oracle database from excel, I get an error of the recommend provider (oracle.dataaccess.client) is not installed. I can connect to Oracle using TOAD with no problem. I've created the 64 bit ODBC data source to the database and the connection tests as okay. Originally the IT group installed 11g and there were issues with it so now I have 12c. When I run vb code in a spreadsheet that from someone else, I get a very similar error about no installation. Within the vb module, I've tried every configuration I can't find in the connectionstring to connect with no luck.