Eclipse-Import -Existing Ant Buildfile-problem

Hello!
Maybe one of you can help me with a problem.
I have a project with it's build.xml.
When I try to import it, I mean to create a project from the existing Ant buildfile, I receive this error:

"Currently only supports creating a project from a single javac declaration".

What can I do to solve it?

Thanks!

I don't see any documentation on this. How is this better than importing an existing project?

Anyway, google search showed some people are commenting out all but one javac, importing and then I guess they are uncommenting.