basic question about grey expert icons

ive never gotten down to the bottom of the idea behind the icons in the experts navigator - when an icon is greyed out as opposed to colored, whats the meaning ?

I have a situation where the expert is being applied "seemingly" correctly to the chart, however its greyed out in the navigator ?

thx

the most common reason for the gray is you only have the ex file and not the mq4.....

another reason it might be gray is if it did not compile correctly.....

//--

the flip side is it can be a normal color even if you do not have the mq4 and it might be a normal color yet still not work.......h

ahh now that makes sense .. thx !