Q:

Singular inconsistent scalar system when connecting a pressure boundary

I am trying to add a pressure boundary to my pipe and get the following error during initialization:
Error: Singular inconsistent scalar system for 
pipe.h_out = ((if boundary.m_flow > 0.0 then pipe.volume.h else 0.0)-pipe.h[...])/( -(if boundar.m_flow > 0.0 then 0.0 else 1.0)) = 2.38651e-009/-0
HandleRoot:HandleRoot

[...] -> Too long for output in the consol i think
Anyone had a similar problem and knows how to solve this?  I am calculating the pressuredifference with a function for dp out of massflow.  Could it be that? 
Additional Informations:
I am using Dymola with the Library ClaRa.  The model in question is a pipe model with the volume splitter for thermal inertia "ClaRa. Components. VolumesValvesFittings. Fittings. SplitVLE_L2_flex".  The model is build up from two pressure boundaries.  One connecting to a supply pipe and one to the return pipe.  The ends of the pipes are connected over the volume to two simple consumer models with each of them having a valve to control the return temperature.  
Update:
I reduced the error to: 
The following error was detected at time: 0
Error: Scalar system is always singular for supply_pipe.volume.p = (0.0)/(0.0) = 0/0
FixInitials:Init

Which only happens when i connect the second consumer to the supply/return pipe.  The model computes with only one consumer.  
Changing the pressurloss model to one that calculates the massflow from given pressure doesnt solve the issue.  

A:

I've found the solution to the problem.  
I've had a resistance to resistance connection between the pipes and a shorting between the connectors.  
Creating another pipe with a volume model at the beginning instead of the end solved it. 