MSB3202 - csproj was not found

Hi,

I'm evaluating TeamCity 8.1 right now and I'm very new to CI.
For testing purposes I've created a Solution in Visual Studio 2012 with two projects named VAG_TestAddon and VAG_Addon_Framework.
In VAG_TestAddon i'm referencing to VAG_Addon_Franework.

VAG_Addon_Framework is located in another path in our SVN.

Building in Visual Studio just workling fine.

In TC i've created two projects, one for VAG_Addon_Framework, one for VAG_TestAddon.
VAG_Addon_Framework has MSBuild as Build Step, whereas VAG_TestAddon has Visual Studio (sln).

How can I resolve the dependency between VAG_TestAddon and VAG_Addon_Franework.
When I try to build VAG_TestAddon i get the following error:
C:\TeamCity\buildAgent\work\40bde373c31baa47\Addon\Addon.csproj.metaproj error MSB3202: The project file "C:\TeamCity\buildAgent\work\40bde373c31baa47\..\VAG_Addon_Framework\VAG_Addon_Framework.csproj" was not found.


Thank you for your help
Matthias