Flame goes out. i have a spc-40 All Pro heater. it lights fine but when i release to gas button

Question

i have a spc-40 All Pro heater. it lights fine but when i release to gas button after 1-2 min. the heater will not stay lit. it stayed lite once and when i moved the heater it went out and will not stay lit. i am lost on what to go with this.