Issues in merging branches

We have two branches. One is a Release Branch (RB) taken from the trunk. The other is a Feature Branch (FB) taken from RB.

We now would like to merge FB back to RB. Ultimately, RB will be merged back to trunk.

I tried to do this with a re-integrate merge, but got the following error:

svn: Cannot reintegrate from 'url://feature-branch'开发者_StackOverflow社区 yet:
Some revisions have been merged under it that have not been merged
into the reintegration target; merge them first, then retry.

Some questions:

1. Should I be using a re-integrate merge to merge FB into RB or some other method?

2. Should I ensure that RB is merged into FB before merging FB back to RB?

3. What is likely causing the above error?

This is with Subversion 1.5

Many thanks

I've had very similar problems myself before and here's how I solved them:

1. Firstly, ensure both branches are updated from the trunk
2. Do a cleanup
3. Ensure FB is updated from RB and fix up any conflicts
4. Do a cleanup
5. Merge FB into RB and fix up any conflicts
6. Do a cleanup
7. Merge RB back to the trunk and fix up and conflicts