Please try clearing the columns before setting AutoGenerateColumns = false;
radGridView1.MasterTemplate.Columns.Clear();
//or
radGridView1.Columns.Clear();
I cannot see here where are you setting the DataSource for the grid, if you are setting the data source before this the grid could have already generated the columns at the point you are setting the auto generate columns to false.
Hope this helps, if you have any other questions or comments, please let me know,
(Off topic and please don't take it the wrong way: the first line was really fun to read :)))