(1) Maybe the collision energy is too LOW. The First MS is not full a fragment.(2) Are you using ESI mode?
(3) If the Molecular weight is 237, for SIM -> Here are three characteristic ions (m/z) 164，149，122 I highly recommend them.
(4) MS-MS (MRM): Need to search online for the product ion and parent ions.
(5) If only need the full scan, why not adjust the concentration of analyte.
Hope it helps.
