I had a similar problem in my shadowrun group. Both players were playing PCs without much leadership potentional. The gunbunny was designed to be too intellectually challenged to make a leader (in her time in the army she made corporal about 6 times, always getting busted back from sergeant) and the mage was too timid and inexperienced to lead.
Since both PCs were clearly not made to lead, I decided to let the players play what kind of characters they wanted, and not force one of them to lead. I introduced a NPC team leader, and things have been going smoothly ever since. The players take the initiative when their PCs have personal goals, but neither wants to play TacOps or Squadleader, so I took over that part.
It makes planning runs and adventures easier - I can set the plan in advance and don't have to react during game, even though I still present the players (not their PCs) with a a couple options to choose from, and all are happy.
IMHO, too many people, even on this board, think you have to force the players to play smart, assertive characters in D&D. I, on the other hand, let my players play followers if they want to, just as I let them play "stupid" characters without punishing them until all are playing smart, paranoid masterminds.
The goal of the game is to have fun, not to force the players to play leaders when they don't want to.