Brake fluid pump/flow problems.

Hi. After changing left rear brake cylinder had no fluid flow in pipe. Tried to pump brake pedal but still no flow. Opened valve on right rear cylinder to see if there was flow on this line but also here, no flow. Pumped brake pedal again but still no flow. Disconnected fluid pump and also no flow through pump with cylinder pressed in. Dismantled pump and it looks ok. A mecanic at local LandRover dealer told me that on some models they had to connect a pump to fluid tank to pressurerise line. Sound strange as fluid thin as water and should flow freely. Excuse my English as I am a Norwegian. Looking forward to see if anyone else have had same problems. Also have 3 Amigos and waiting on brake light switch. Could there be a valve in the ABS unit that blocks fluid as I have ABS yellow light on panel?