97 terry hot water problems

Hi I have a 97 terry 32 foot camper with atwood mpd-91043 gas valve I replaced the thermocouple from one I bought at homedepot the pilot light stays on but as soon as you switch it to on it goes right out and every now and then you can get it to light and it will heat up the tank and then go right out pilot light and all I did clean out the tube with a vacume, the problems started happening shorty after running out of propane, how can I fix this, thanks