I grouped a shape i had created using ctrl + G. duplicated the shape and used the inset tool how ever its not letting me inset?

Hi.

Inset works on paths, not on groups. You should enter the group for insetting (Ctrl+Enter) and select the objects inside (Ctrl+A).
If that's a rectangle/ellipse, they will be converted to paths (?) and if it's a text it may need to be converted to a path first (? not sure, didn't test).
And in general, Boolean operations result in closed paths -open paths will be closed after insetting probably.