I'm guessing Control[0] is not actually a checkbox.
Set a breakpoint and you might find it to be a <TD>.

Rather that going after it by index, how about trying the control id as in:

VB Code:
  1. sParams[3] = CType(e.Item.FindControl("<id>"), CheckBox).Checked.ToString

This should give you "true" or "false".

Not that I recommend storing such values in the DB