Using Document Management: Fields value are not getting populated when added in Header/Footer area of MS Office Word Document

I am working on Document Management utility in Microsoft Dynamics AX 2012 R2. I found a problem that when I am adding the field in the body area of the word document, the output shows the value. But if the field is added to the Header/Footer area of the word document, the output displays the field name name or label instead of the value in Header/Footer area.

Anyone have idea about this. Why it is happening.