I am populating a gridview from a database

Code:
 sql = "SELECT* FROM tblFaultlog ORDER BY sys_date ASC"
            GridView1.DataSource = sqlquery()
            GridView1.DataBind()
sqlquery return a datatable with the information I need, I do populate the datatable with some data but in the gridview I make one column.visable = false

Why is it that if it is not visable I can't call on that column progromatically?

it's as if the gridview doesn't retain the data for that column.

Thanks in advance.