I'm doing a remodel for a family member and I can't get the three fluorescent light fixtures to all light up off one switch when I turn the switch to the on position the middle fixture will light up completely but the other two won't .I ran power from the switch to a j box in the center of the room then I tied all three fixture to it

OK, power should go to the switch box, then to the junction box and then to each fixture. In the switch box the neutrals (white) should be connected together with a wire nut. Each hot (black) should be connected to the switch. In the junction box all the whites should be connected together with a wire nut. All blacks should be connected together with a wire nut.
Fixtures should be connected white to white and black to black.

The modern day floresent fixture must be grounded. If not grounded the fixture may not light.

Hello.

Power can also be brought to the switch. Open the outer sheathing of the cable in the area of the switch only. Separate the white and black conductors. Cut the black conductor, strip both ends of the black condudtor. The side of the conductor leading to the power source gets connected to the bottom of the switch. The black conductor leading to the J box is connected to the top of the switch. The white conductor bypasses the switch without interuption.

Is the hot lead at the wall switch or in the junction box.

The power source can be at either locatioon.

If power source comes ino the overhead J box, then you need to run a switch loop to the switch.