Bind checkboxlist with char value

Question

Anyone knows to retrieve checkboxlist from database that has char value " , " and single value ?

Object not set to reference - if (PortItem.Users.ToString() != null)

if (PortItem.Users.ToString() != null)

{

char[] spl = new char[] {  ' , '  };

string var = dsPort.Tables["Ports"].Rows[0]["Users"].ToString();

string[] arr = var.ToString().Split(spl);

for (int i = 0; i < arr.Length; i++)

{

if (arr[i].ToString() != "")

{

ch_Users2.Items.FindByText(arr[i].ToString()).Selected = true;

}

}

}