You don't shake it, you sort of thrust it up and down in the water (don't ever bring it above the surface of the water). The outlet end of the tube needs to be lower than the inlet (in a bucket on the floor). The idea is to get rid of the air in the tube so the thrust just forces water up until its full and syphoning begins (it only take about three firm thrusts).
I find that the more water there is, the easier it is to start it. You're not trying to use a large syphon on a goldfish bowl are you?
Also, if you need to temporarily stop the syphoning whilst you change buckets, just pop your finger over the end of the outlet end.
Pauly.
LOL - no, not a golfish bowl (thought of that is hilarious) - it's a 3ft tank. Oh, and I was thrusting rather than shaking (although "shaking" sounds a politer word
I think where I went wrong was that (a) it wasn't fully submerged and full of water and (b) I didn't hear any clicking noise (as suggested above) and © I'm just plain useless!!
Thanks again guys for the input - it's given me the incentive to give it another try...
hehehe somehow I managed to copyright myself being plain useless..! (see above)