Server ErrorControl ctl00_ContentPlaceHolder1_grd of type GridView must be placed inside a form

Control 'ctl00_ContentPlaceHolder1_grd' of type 'GridView' must be placed inside a form tag with runat=server. 

when i am try  click to  view file using html blank page it say error like below;

Control 'ctl00_ContentPlaceHolder1_grd' of type 'GridView' must be placed inside a form tag with runat=server.

anyone know help me for i am resolve it.

thanking you,

Paul.S