c# - DataGridViewRow Wrong Cell Index -

i've got problem while trying values through datagridviewrow. problem cell index 7 , when try data cell using code:

 foreach (datagridviewrow r in this.mydatagrid.rows)         {             if (convert.toboolean(r.cells[0].value) == true)             {                 datagridviewcomboboxcell cc = (datagridviewcomboboxcell)r.cells[7];                 cc.value = toolstripcombobox1.selecteditem.tostring();                 edit_subject(convert.toint32(r.cells[1].value), r.cells[7].value.tostring());             } 

an exception error comes saying cells[7] outofindex . i've tried change cell index 7 5 , it's worked , , no .

please need explain because it's weird.

ok found solution, problem caused because sql syntax (the datagrid datasource) has different order datagridview columns, didn't because datagrid autofill has been disabled . , i've set datapropertyname each column manually.

anyway , response.