Help with RO/DI

[garnet13aj]

Sorry, the title is wrong and I don't know how to fix it...
I just moved and am having trouble starting the siphon on my overflow box for the sump. My boyfriend originally set it up at the old house so if there's a trick I don't know about it.
I set it up, turned on the pump and the water started rising above the overflow box but when I suck the tube to try to start the siphon nothing happens. Am I missing some key component of the process?

 

[yukon]

Not sure how to change the title but I'll try to help with the OF
Did you get all the air out of the U tube?
I fill up both sides of the overflow box with water and use a airline hose pushed up to the bend at the top of the U tube and suck all the air out. Once it is full of water you should be good to go.