WebGrid MVC 3 loses sorting if column is formatted ( format: @<text>) or throws null exception on sorting

WebGrid MVC 3 . Webgrid throws System.NullReferenceException: on sorting. This happens if any of the column value is null . If I use following code to check for the nulls

grid.Column( columnName: "IncomingFile.Name", header: "IncomingFile.Name",  canSort: true, 
            format: @<text> 
                @if (@item.IncomingFile != null)
                {@item.IncomingFile.Name} 
             </text>),           

Then the webgrid loses its sorting c开发者_运维知识库an anyone help how to solve this.