title: DatagridView Checkbox Column is always null
body: <p>I have a strange issue.
  Basically I have a datagridview and a button. When I click this button it checks all rows for column 1s value - the checkbox column. It then sets it to true / false depending on what it currently is.</p>
  
  <p>Thats all fine.</p>
  
  <p>But then, I have another button to do something with these rows that are ticked. I click it and it only ever identifies the first row as being ticked. The rest are apparently null now..?</p>
  
  <p>So, how can I programmtically set the value of a checkbox column in a datagrid view and then read it again cause Im apparently way off the mark based on my results.</p>
  
  <p>This sets the tick boxs and I can see them, untick them manually etc.</p>
  
  <pre><code>foreach (DataGridViewRow row in dgv.Rows)
          {
              var ch1 = new DataGridViewCheckBoxCell();
              ch1 = (DataGridViewCheckBoxCell)row.Cells[0];
  
              if (ch1.Value == null)
                  ch1.Value = false;
              switch (ch1.Value.ToString())
              {
                  case "True":
                      ch1.Value = false;
                      break;
                  case "False":
                      ch1.Value = true;
                      break;
              }
          }
  </code></pre>
  
  <p>Then the next button to check values is just finding nulls</p>
  
  <pre><code>foreach (DataGridViewRow row in rows)
              {
                  var ch1 = new DataGridViewCheckBoxCell();
                  ch1 = (DataGridViewCheckBoxCell)row.Cells[0];
  
                  if (ch1.Value == null)
                      ch1.Value = false;
                  switch (ch1.Value.ToString())
                  {
                      case "True":
                          ch1.Value = true;
                          break;
                      case "False":
                          ch1.Value = false;
                          break;
                  }
                  var val = row.Cells["EbayListingID"].Value.ToString();
                  if (ch1.Value.ToString() == "true") continue;
                  var listing = dsEntities.EbayListings.First(x =&gt; x.EbayListingID.ToString() == val);
                  SubmitListingForReview(listing, false);
              }
  </code></pre>