Why Itemscontrol is inconsistent with item source in datagrid wpf? - data-binding

Question

When First time I open the form, datagrid shows data but when I open other form and again open this form this it gives error Itemscontrol is inconsistent with item source
This is my Datagrid in which is used to bind the list.
```
<DataGrid.Columns>
<DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTextColumn Header="Description" Binding="{Binding Description}" Foreground="Black" IsReadOnly="True" />
</DataGrid.Columns>
</DataGrid>```
here on form load function , the datagrid loads.
{
// dtGrid1.Items.Clear();
DataTable dt_Grup = new DataTable();
DataTable dt_Type = new DataTable();
try
{
dt_Grup = dal.Select();
for(int i=0; i< dt_Grup.Rows.Count; i++)
{
FeeGroupControlShowBLL ck = new FeeGroupControlShowBLL();
dt_Type = dal.Select1("SELECT tblFeeType.Fee_Type_Name, tblFeeTypeGroup.Amount from tblFeeTypeGroup inner join tblFeeType on tblFeeTypeGroup.Fee_TypeID = tblFeeType.Fee_Type_ID where Fee_GroupID = '" + dt_Grup.Rows[i][0].ToString() + "'");
ck.groupName = dt_Grup.Rows[i][1].ToString();
ck.Description = dt_Grup.Rows[i][2].ToString();
for (int j = 0; j < dt_Type.Rows.Count; j++)
{
string Type_Amount = (string)dt_Type.Rows[j][0] + " Rs" +(string)dt_Type.Rows[j][1];
ck.FeeTypeName.Add(Type_Amount);
}
b.Add(ck);
}
dtGrid1.ItemsSource = b;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally
{
db.con.Close();
}
}```