Offset Section area got Enclosed

Hello,

I have an assembly in which I am creating section by using offset feature.

After making the sketch to define the area of section the section comes up with an enclosed box.

Attached below the few screens shot of the assembly.

1. Plan view of the sectional area.

2. Isometric view of the section in shaded mode. Here you can see the enclosed surface and my section got covered by this object

3. Isometric of the same section but in Wireframe mode. Hereyou can see the section but still enclosed with a box.

Any suggestion how to remove this ??

Thanks in advance

Yogesh