rebase fails but not sure why

I have been doing repeated rebase on my repository to try and separate out mixed streams of development into separate branches.

I have now got to a point where the following error occurs during a rebase.

fatal: empty ident <alan@chandlerfamily.org.uk> not allowed Commit failed, please do not call "git commit" directly, but instead do one of the following:

When you have resolved this problem run "git rebase --continue". If you would prefer to skip this patch, instead run "git rebase --skip". To restore the original branch and stop rebasing run "git rebase --abort".

but I am not sure how to solve issue.

git status shows a number of files waiting to be commited, but no unmerged files. but git rebase --continue just pumps out the same error message.