Getting the parent branch through tfs API

Hi

I'm trying to get the name of the parent branch through the TFS API.

(TFS 2010 and VS2012)

Assume a branch trunk to child1.

Input "changeset" is the changeset where a given branch is created.

    ChangesetVersionSpec csv = new ChangesetVersionSpec(changeset.ChangesetId);
    BranchHistoryTreeItem[][] branchHistoryTree = mVersionControlServer.GetBranchHistory(new ItemSpec[] { new ItemSpec("$/Project/child1", RecursionType.None) }, csv);    var treeItem = branchHistoryTree[0][0].GetRequestedItem();
    if (null != branchHistoryTree[0][0].Parent)
       //Parent is always null

What would be the right query to perform, to get this info ?

PS
The child1 branch doesn't exist anymore, in a 2008 TFS it was moved to a new name, say "release1". I dont think that matters though, as I can read all other information of these "moved" change-sets.

Hope.....

BR Henrik.