The screen wash ran dry, I refilled it, but no water was pumped through?

The pump seems to work from the sound it makes but no water pumps through the water jets (front or rear). I have flushed the system and water goes through the pipes and jets. I have also fitted a new electric screen washer pump but still no water through the jets. How do I get the washer working again?

Vauxhall cavellier 1.6 - N reg.