Fluorescent bulbs of the tube type have two different style ends on them. Some bulbs have a single nipple in the middle of each end and some have two prongs on each end. Installing a fluorescent tube bulb can sometimes be difficult if the prongs do not set in the cradle correctly. Installing a fluorescent tube bulb takes less than a minute.
Examine the tombstones on the fixture that requires the tube with the single nipple on the ends. One end of the fixture is spring loaded and presses in when the bulb is inserted. Insert the tube bulb into the spring loaded end first and press it in with the bulb then slip the nipple on the other end of the bulb into its receptacle. Allow the spring loaded end to pop out so it holds the bulb in place.
Locate the tombstones on the ends of the fixture that require the tube bulbs with two prongs on each end. Notice that the receptacles have two channels, one in back of the other.
Hold the tube bulb so the prongs are vertical.
Place the top prongs into the back channels. As you push the top prongs into the back channels twist the bulb clockwise so that the bottom prongs fit into the front channels. Push the bulb into the channels and ensure that it is securely in the channels on both ends.