VelocityModel: Pedestrians are too near to each other

The application of the velocity model reveals the following error:

Time: 123.70 s | Evacuated:    42 / 2086 (  2% ) [=>                            WARNING:   ]   
 in VelocityModel::forcePedPed() ep12 can not be calculated!!!


Pedestrians are too near to each other.
Get your model right. Going to exit.

UBF_dummy_id_0_seed_3011.xml UBF_geo.xml