Oracle 10.2.0.4 patch from oracle 10.2.0.1 giving error

Hi Experts,

I have installed oracle 10.2.0.1(software only) in windows server 2008 R2(X64).

Now I want to patch this to oracle 10.2.0.4 version.

I have downloaded the patch and extracted and run the installer.

Now when I choose the oracle to patch, it gives the error that 'this can be used on an existing oracle home only'.

Also in the 'installed product' button, this is not showing any software details.

I am not able to understand what is the reason for this error. Please help.

Thanks,

Arijit