Value not available for invisible columns

have you tried looking cells[x].value - cant remember off the top of my head if it exists but its where i would start looking.
I'm already using Cells[x].Text (value does not exist)

When a boundfield's visiblity is set to false, its value is not included in the data that is returned to the client.

not sure what you are attempting to achieve, but you can always test for null values in theRowDataBound event, if that's about what you need

have you looked into using DataKeys?

http://msdn2.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.datakeys.aspx

http://forums.asp.net/900590/ShowPost.aspx
I realised I could use the Row.DataItem property to just grab the source record instead of messing about with invisible columns etc. Once again when I finally find my solution its simple!
We resolved this by adding a 'ReadOnly="true"' to the asp:boundcolumn control.

vr, Rich