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

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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