I don't see any result at all in the sheet you have posted and also I don't see any attempt to minize a function. You have defined some range variables which are not used at all (resp. have no efffect) and I guess the function dE() you defined isn't working as you expected. It will only return the derivation of E after Phi for B=60 in every case - the range has no effect. What should dE() return in your opinion?
And which expression is it you want to minimize?