SVN labelling issue

I'm trying to label a build that is made of multiple checkouts like this:

+Root
+-trunk
+--Folder1
+--Folder2
+-Tags
+--ProjectA
+---Build-123
+----Folder1
+----Folder2

where 123 in Build-123 is the build number.
I'm trying to achieve this by using the following labelling rules:

/Root/trunk/Folder1=>/Root/tags/ProjectA
/Root/trunk/Folder2=>/Root/tags/ProjectA

And this labelling pattern:

BUILD-%system.build.number%

I was hoping that TeamCity would create the BUILD-123 tag and copy the contents of Folder1 and Folder2 into it. However I get the following error:

Failed: Failed to set label 'BUILD-123': Svn labeling failed: Cannot copy 'Root/trunk/Folder1', 'Root/trunk/Folder2' to the same directory 'Root/tags/ProjectA/CO-BUILD-123'

I'm using TeamCity 5 with Subversion 1.6