While you're waiting to hear back, what you really need to do is make a list of concrete and measurable reasons WHY you should get a raise. Just playing the seniority card isn't a good enough reason.
How has your position changed since the last increase? What additional duties do you perform? What additional value are you bringing to the company?
In my mind, an employee should NEVER base the reason for wanting a raise on the salary of another co-worker.