Ideal pump issue in Simscape model (2P)

i have an issue with my simscape model in 2P domain. I use Controlled Volumetric Flow Rate Source (2P) to create flow at 5m^3/hr and when i start the model for a very little time i receive an extreme flow rate like -500m^3/hr. Why this?

[nick]

Kindly attach your Simscape model along with your question to help resolve the issue effectively.