Reaction of Diazonium salt with Grignard reagent?

Why doesn't Grignard Reagent undergo Nucleophilic Substitution with a Diazonium Salt? for example if we want to convert phenol to p-cresol. Then first nitrating it, then convert it to a diazonium salt and treating with a methyl grignard reagent. But the reaction dos not happen. Instead we have to use Gilmann Reagent for this process. Why?


