Oracle upgrade 10.2g to 11g

Hi

I have an ides system installed on Oracle 10.2g.

Is it possible to upgrade to 11gR2 without using SAP's packages.

I have installables on Oracle 11gR2.

I have tried it for test purpose, installed the 11g and now while running the DBUA, I get the error that ORA-01507 database not mounted.

Please guide