C1 DataGrid Filter Adhoc Row issue

Hi,

we are using following code to add Adhoc Filter Row in C1DataGrid but some times it is in Disable State.

datagridDisplay.Rows.TopRows.Add(New Goldcrm.Controls.Filter.clsFilterRow(datagridDisplay))
Please find the attachment with this.
Please give me any solution for this.

Thanks in Advance,
Naveen