EA grayed out

 
When looking in my Navigator window, why are some of the EA icons grey and some in color? What's the meaning? How do I turn on the grey ones?
 
F1 - User Interface - Navigator
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Experts' icons colored in grey mean that these experts cannot be used. Such expert must be compiled first.
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Forex Trader #:
F1 - User Interface - Navigator
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Experts' icons colored in grey mean that these experts cannot be used. Such expert must be compiled first.
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Said in another way; you forgot to compile your EA or it got turned off. While in navigator, select broker account, right click on the grey EA you want to run, and select Algo trading. This will turn on or compile the EA. The EA icon will turn from grey to blue in navigator, and in the upper right meta trading screen. In other words, this will compile/turn on the EA to blue. 
Reason: