Gillingham agreed to the move but McCammon turned it down.
"I made the call and Mark Stimson was happy for us to have him but sadly the lad didn't want to come," Dover boss Andy Hessenthaler told BBC Radio Kent.
"That's his prerogative. It was another option for us but it didn't come off."
He added: "We tried another lad - we won't name any names.
"Again we could have done the deal but the travelling was too much for the lad and that's what goes against us a little bit."
Dover also failed in a bid for Gillingham defender Tom Wynter, as manager Mark Stimson may still need him in their fight for League One survival.
And the signing of Barnet defender Ahmed Deen was cancelled because the league will not let a manager have three players from the same club on loan at the same time.
Source: BBC Sport
Source: BBC Sport