Topic: Calibration's problem

I'm studyind a negative spectrum about a speciment of PDMS from ION-TOF5 and trying to calibrate I found impossible to complete a correct calibration. I tried saving in annotation the reference elements(H, C,CH,CH2,CH3,O,OH) inserting the correct value for m/z (ex: 1.00794 for H); I triend the linear and the quadratic calibration but a lot of significant elements wasn't at the right value of m/z (like observed in literature).After it, I tried using the icon about re-calibration data using a reference masses library where I had entered the same elements (H, C,CH,CH2,CH3,O,OH) but nothing better then the first trying.

Can you help me!!
With kind regards,