Error building search tree

Hi;

I have a problem running my Mike 21 FM model.

I created a mesh with numerous quadrangular domains and get the following message when trying to run the model:
Fatal Error: InsertElementd2DSearchTree: Error building search tree – Possibly erroneous mesh – Abnormal completion.

Where could the problem be from? From the mesh itself I suppose but I don’t know which conditions the mesh needs to fill for the model to run without mesh geometry linked errors…

I actually have some land boundaries within my network; might this be the reason? I didn’t find any solution to erase them from the mesh generator.

Thanks by advance for hints you might give me.

Best regards

J.R