Digital BW, The Print

After tiring of refillable cartridges, I decided to buy  a JetStream CIS.

Last night I printed some purge sheets, and a couple of images -- everything seemed okay.

Today, the printer won't print a thing. I've run several cleaning cycles, used SSC's power 
cleaning mode, charged the heads but nothing seems to be getting the ink to flow.

The tubes seem fine, no bubbles. Everything is as it was last night. Is this normal?

FWI, I'm using C6 inks.