Toyota Repair: 2000 prerunner rear dif, toyota tacoma prerunner, rear diff lock

Question
I have a 2000 toyota tacoma prerunner v6 with 75000 miles on it.  When I select the rear diff lock button it won't engage the light just blinks.  I can hear the rear end trying to lock if i listen with the window down.  i have tried to ease fwd and back but no luck.  What do you think is wrong.

Answer
I checked the repair manual and it says that if the light flashes it means that the differential locking gears are not meshed and recommend driving the vehicle foreward until the gears mesh and the light goes off and the gears lock, this should only be used off-road and not on pavement.