C# Winform Using DGV Filter pop up plugin in Datagridview

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C#

DataGridView

Hello, here's the scenario, i am able to show popup in datagridview using this code

Form_Load

DgvFilterManager fm = new DgvFilterManager(dataGridView1);

For the Table

MySqlCommand cmdDatabase = new MySqlCommand("Select * from del", con);
{
   MySqlDataAdapter sda = new MySqlDataAdapter();
   sda.SelectCommand = cmdDatabase;
   System.Data.DataTable dbdataset = new System.Data.DataTable();
   sda.Fill(dbdataset);
    BindingSource bSource = new BindingSource();
    bSource.DataSource = dbdataset;
    dataGridView1.DataSource = bSource;
     sda.Update(dbdataset);
 //
 }

And it works, now i tried to put a Checkbox in the datagridview using (Designer) , after doing it, I got Error:

DgvFilterManager fm = new DgvFilterManager(dataGridView1);

An unhandled exception  of type 'System.NullReferenceException' occurent in DGVFilterpopup.dll

Object reference not set to an instance of an object

I hope this helps DataGridView Filter Popup[^]

Please help, i need the DGV to work with checkbox please