It seems to me you did things in the right way.
1) Check your spelling in setEnv.cmd again to see if you made any typos;
2) CAREFULLY check if you put any invisible character after classes12_01.zip. Invisible characters such as spacebar are very, very insidious.
3) This is a double check. Go to MS-DOS.
GO to C:\weblogic. Run setEnv.cmd. Then run startWeblogic.cmd. DONT, DONT, DONT run Weblogic for Start|Programm Files|Weblogic.... Thats for lazy guys and there are some glitches in that direction.
Use MS-DOS. Be sure!
4) It is not a good idea for us to put jdbc or other alien classes under JDK. The reason is that we need to un-istall JDK frequently.