Set the sorting properties of gridview true but still columns are not becoming links

I have to do a sorting on headers of the gridv开发者_StackOverflowiew.

i have set the sorting property to true and also implemented the onsorting event.

But my headers are not coming up as links,what could be the reason?

Maybe your columns content is not sortable, for instance you have images. For that as a trick you can associate each image an index and bound the grid column to the index, rather than image.