Why doesn't my spline become a solid filled object?

[Anonymous]

Hello, I'm trying to draw a heart, i made this spline and closed it at the origin (even the message "close spline?" And I said yes), however, when extruding, the internal part of the object is not filled, only this small thin part is extruded. internally it is "empty", what can it be?

without extrude command, spline finished

when i tried extrude command, the internal area not "filled"

[Anonymous · Accepted solution]

Perhaps you have overlapping vertices in your spline.

Add a normalize spline modifier with an edge length of 0.8 or something.

[Anonymous]

Thanks, it's works. 
I'll try apply material on object now.