Order Placement Trading Functions require that the "Allow live trading" property of the selected expert advisor is checked. You can check the settings for an expert advisor within the MT4 terminal as follows.

Select the chart within the Metatrader 4 terminal that contains the expert advisor that you wish to allow live trading. Press the F7 key or right click and select "Expert Advisors" and "Properties" as shown in the picture below.

Next, select the Common tab. This should be the first tab as shown in the picture to the left. Look down to the section on the left titled "Common" and make sure the positions dropdown box is set to "Long & Short" if you wish to have the expert advisor place both long and short orders. Alternatively, you may select "Only Long" or "Only Short" if you wish to only have the expert advisor to initiate only long orders, or only short orders respectively.

Also shown in the picture to the left, look down to the "Live Trading" section. Make sure the "Allow live trading" check box is checked. As an additional check, make sure that Expert Advisors are enabled in the Metatrader 4 terminal. Look to make sure the "Expert Advisors" button is depressed. A depressed "Expert Advisors" button appears in the toolbar at the top of the MT4 terminal has a green circle with a white arrow facing right in the graphic as shown.     When expert advisors are not selected for live trading the icon at the top in the toolbar will have a red circle and a white square in the middle. You can toggle expert advisors on or off on the entire account by clicking the Expert Advisors button. This may also be done globally within the Tools/Options menu on the Expert Advisors tab as shown in the picture below.

Note that the "Enable Expert Advisors..." check box needs to be checked to enable expert advisors on this MT4 account. In the picture this box is unchecked meaning expert advisors are not enabled. Make sure the "Allow live trading" box is also checked if you wish to have your expert advisor place entries and exits either on a demo or live Metatrader 4 account.