Nautilus II Reef dosing pump ?

[NewSchool04]

I have a Nautilus II reef dosing pump (www.innovativeaquatics.com) and I can't get the tubing that goes around the black rotor to stay on the connectors. It slowly gets pulled off after about 3 minutes.
Anyone have this happen and know what to do about it?

 

[ostrow]

Did you trim it too short? That's the only thing I can think of.

 

[NewSchool04]

i trimmed less than 1/4" because I couldn't get it to work before.