How to resolve conflicts in SVN?

Hi all,

I'm facing a bug, and I'm not sure if the problem lies on an image library, so I commit it as revision 36, for example, and porting the program to another image library.

After porting, I found the bug is nothing to do with the image library, however, I still commit it as revision 37 for further examination.

Then I back to revision 36 to further improve my code, however, when I want to commit, it prompts out that there are some conflicts, for instance, foo.cpp.

I try to resolve the conflict by "svn resolved foo.cpp", system outpus:
Resolved conflicted state of 'foo.cpp'
However, when I commit again, the commit still not allowed by SVN...

So how can I resolve this problem?

Thanks!