How to adjust column width at runtime

I have created a datagrid by codebehind and want to adjust the column width at runtime. I did this: I got an error that : ... Index is out of range. I then compared data in the grid and data in the datatable to check if there is any data in the grid. I could not find any. I checked like this : The result was : 0 vs 6. However, the code runs fine. I see all 6 columns with data in the grid. What is be wrong here. How can I access data bound in the datagrid and adjust the width size? Please help. Thanks for helping.