If you can get one to work, you must have the tools basically configured, surely?
So you just need to get debugging to find what mistake you've made in your "Hello World."

Note that you can load any Hex file into the Keil simulator - so just load the Dunfiled Hex into the uVision Simulator and step it through to find the bug.
(you probably won't get symbolic info - but you should be able to see what's going on with the aid of the dunfield listings & map file...)