Help: Customized Indicators will not Attach to charts!

After loading the Custom Indicator from such sites as ForexFactory, Forex-tsd, and even MQL4, into the FXDD-MetaTrader4/experts/indicators file, and then highlighting the Indicator in Navigator and then right-clicking on the message: Attach to a chart, nothing happens. I have recently reinstalled MT4 and it seems that the Custom Indicators that appear with the download installation of MT4 work and will attach to the chart. But, most, but not all, new custom indicators will not work. Upon clicking on the Attach to a chart, the message disappears and nothing happens., the Custom Indicator screen does not appear. Any suggestions? Thank you, JohnO