Could be the ballast. This one should work for Sam versions.
GE Lighting 68186 GEM120PH120DIY LFL Magnetic Rapid Start Ballast for 1- F20T12, F15T8, F1512 - 120V Magnetic Ballast (200H2) https://www.amazon.com/dp/B000HMBPM8/ref=cm_sw_r_cp_tai_ZxyYxbSD9P3F9
It's hard to give specific help without more details.