problem with link button c#

Hello experts,

I have a problem with a grid, i created a grid with a query, then i would like to add a button link, but it give me an error, this one

The type 'SAPbouiCOM.GridColumn' can not be implicitly converted in 'SAPbouiCOM.EditTextColumn'. An explicit conversion already exists (check if a conversion is missing) and my code is

oForm = oApp.Forms.Item("formpri");
           
            oForm.Visible = true;
          
            oitem = oForm.Items.Item("grdpy");
            oGrid = ((SAPbouiCOM.Grid)(oitem.Specific));

            oForm.DataSources.DataTables.Add("grPagdt");


            oForm.DataSources.DataTables.Item(0).ExecuteQuery("SELECT PayMethCod AS Código,Descript as Descripción,Active as Activo from OPYM where type='O'");
            oGrid.DataTable = oForm.DataSources.DataTables.Item("grPagdt");
            oGrid.Columns.Item("Activo").Type = SAPbouiCOM.BoGridColumnType.gct_CheckBox;
            SAPbouiCOM.EditTextColumn gridEditCol;
//here is the error
            gridEditCol = oGrid.Columns.Item("Activo");
            gridEditCol.LinkedObjectType = "13";



thank you