I'm not sure whether Win2012 comes with MSDAORA or not as I don't have one handy to check, but the "usual suspect" here is that MSDAORA only comes in 32 bit (they didn't port it to 64 bit). As such, you can either use it with a 32 bit app (even though the OS is 64 bit), or use an OLEDB provider that DOES come in 64 bit (such as Oracle's - OraOledb.Oracle).
Note that there's a known issue that affects an 11203 install where the Oracle provider doesnt get registered by default (although it's installed). Just run regsvr32 on oraoledb11.dll to fix that.
Hope it helps,