I want to install a new light fixture in a bedroom. The old quit working so I thought I would just replace it. However, after taking the old one down and replacing it, the light will not work. I have a volt sensor and it indicates there is voltage. I’m getting voltage even when the fixture is not hooked up.  I hooked it to another room and it worked fine (lights and all).  How can there be electricity running through wires but the light won’t turn on? The breaker is not thrown. The light just won’t work. It is an older house. 1950′s. The wiring is original. Wiring connection is white to white and black to black, right? Why won’t the darn light turn on? And yes, the light bulbs are good.

Sorry to hear that your fixture is still not working. Because your old existing fixture stopped working it seems that there is another problem with the fixture circuit. The voltage reading you are getting could be caused by a condition known as a Neutral Feedback. If this is the case, the Hot Conductor has encountered a loose connection, or even possibly burnt itself apart. Typically this will be found at another junction box found somewhere in the vicinity of the bedroom. This is discovered through a process of elimination. If you know which breaker or fuse feeds this circuit then it should be shut off before proceeding. The fault is usually discovered by opening and checking each junction box. Many times shorts such as these are found in other ceiling fixture boxes such as a bathroom or kitchen. Older ceiling fixtures created a lot of heat which can cause brittle and cracked insulation over time, and with a home of this age there may be connections that are affected and coming apart. This is a serious situation because if it is a connection that is shorting this is a potential fire hazard.
Given your situation I would recommend calling a licensed electrical contractor who will be able to perform the proper tests, locate the problem and make the repair. Depending on what is found, you may want to consider an in-depth inspection performed for the entire electrical system, especially at the circuit panel.