connection problem with database MS Access

public partial class partmaster : Form
   {
       private OdbcConnection con = new OdbcConnection();
       private basecon obj = new basecon(); //basecon is a class file

private void partmaster_Load(object sender, EventArgs e)
       {
           grid();
       }

 private void grid()
       {
           dgvPartMaster.Columns.Clear();
           DataGridViewTextBoxColumn dgvCol = new DataGridViewTextBoxColumn();
           con.ConnectionString = Microsoft.VisualBasic.Strings.Trim(obj.connection().ToString()); // error is showing (Format of the initialization string does not conform to specification starting at index 0.)
           con.Open();
           string qry;