I'm really confused by the 2 different editions of SQL Server 2012. There is RTM and SP1 which both seem like different code branches. How do I upgrade an RTM install to a SP1 install. I've tried upgrade and that doesn't let me choose the old RTM install.
But you ARE an admin, right?
No. it is the same like any SERVICE PACK. RTM is the released original, SP1 the first service pack. EXACTLY the same like XP, Windows 7 - not windows 8 where the SP is called 8.1. Same like exchange. Like any enterprise software.
Download the SP1 installer, run it.
Why not? Check version numbers. We need a lot more info. For example error info, or what it sees - there is a nice dialog telling you which windows versions you have installed.