Metatrader4: How to enable or disable Expert Advisor...

1. Check the toolbar icon for Expert Advisor

• Green - Expert Advisor enabled 

• Red - Expert Advisor disabled
  
   

2. How to set Expert Advisor to trade (EA is enabled but EA doesn't trade)

(1) Main Menu->Tools->Options

(2) Expert Advisors Tab-> Allow automated trading->OK

(Repeat first 2 steps to check the new configuration) Main Menu->Tools->Options->Expert Advisors Tab-> Allow automated trading->OK