patio heater pilot takes forever to stay lit?

My patio heater works like a champ when it's lit but lighting is another story.

I depress the valve,depress the ignitor button and all works well. The pilot lights. BUT,I have to keep depressing the valve for over ten min before the pilot will remain lit.

I thought this was maybe a thermo coupler problem(I'm not really sure if my heater has one or a piazo)and that it wasn't heating up fast enough on first lighting. BUT...

My bottle ran out and I immediatly changed to a full one while everything was still hot and STILL had to re-light the pilot by holding ten min.

I've checked the pilot gas tube for any webs,blockage,etc and double checked that all couplers are secure with no leakage.

HELP?

Wade
December 2009