2018 OCR A level exploring physics - question 25a)ii)

oxygen + proton => Florine + neutron + gamma ray

oxygen has binding energy 2.24*10^-11
Flourin has binding energy 2.20*10^-11
the proton has kinetic energy 0.25*10^-11

the question is find the energy of the gamma ray

for my soloution I added the kinetic energy of the proton with the binding energy of the proton and subtracted the binding energy of flourine to find the energy of the gamma ray but the mark scheme said that was wrong. can anyone tell me why?