Server Error when sorting from server-side

[Forrest]

Greetings,
  I have a RadGrid within a CompositeControl (along with a couple RadMenus and some other controls). I store a user's column visibility and sort preferences serverside and manually add the columns and sortexpression when a grid is loaded. The error I am getting is:

Unable to cast object of type 'Telerik.Web.UI.GridImageButton' to type 'System.Web.UI.WebControls.Button'.

which occurs Only when I add my own sortexpression to the mastertableview during Grid.Init (after all the columns have been added). If I comment out the

Grid.MasterTableView.SortExpressions.AddSortExpression(sortExp);

then everything works as expected, but I don't get my sort, of course.

I have tried setting Col.ShowSortIcon to false but that did not change anything. I have also played with different values for Col.HeaderButtonType, also without change.

Any insight would be greatly appreciated.

Thanks,
 - Forrest

[Forrest]

Bump..

[Nikita Gourme]

I am not familiar with your composite control implementation, however it seems to me that the sort icon displayed in the column header is attempted to be cast to Button while it is actually GridImageButton. I read about the CSS sprite buttons for the grid elements here and this might be connected to the matter. Check your code for any explicit casts to Button for grid images, this might give you some clues.

Nikita

[Forrest]

Thank you very much for the reply.

Unfortunately, I never touch anything regarding rendering in the header columns of the grid. But that does give me an idea on how to approach this, thanks. I'll let you know how I fare.