When you install a new indicator in MetaTrader (i.e. copy a new indicator into the Experts\Indicators folder), probably MetaTrader won't recognize the new indicator because you have added the indicator while MT was open.
Remember that to install a new indicator properly you have to copy the file before turning on your Metatrader station. If you have copied the file while MT was open you just have to restart (close and open) the software. In any case you should find the indicador in the Navigator under Custom Indicators.
Finally if this solution doesn't work, make sure that you're installing an indicator and not other type of file such as an Expert Advisor.