Maven internal repository

Hi,

I am a student and we are developing a software project. I have installed an internal Maven repository exclusive for our artefacts on the server computer. I can access it with http://hostname/internal. Its layout is same as in a Maven remote repository. There are already some artefacts in it. But

<project>
  ...
  <repositories>
    <repository>
      <id>my-internal-site</id>
      <url>http://hostname/internal</url>
    </repository>
  </repositories>
  ...
</project>

in pom.xml don't work. What have I done wrong?

Thanks beforehead,
regards