Error generating query in datatable with linq and backgroundworker

I am using the BackgroundWorker component to generate a task in the background, what I do is traverse a datatable and execute a search in a second datatable to verify if the data to compare exists, if so, then execute a store procedure.

The problem I have is that when making the query in the datatable using linq leaves the backgroundWorker and does not perform the task, I want to know how to correct this situation.

Archivo archivo = new Archivo();

        dta = (DataTable)dgvRegistros.DataSource;
        dta1 = (DataTable)dgvProcesado.DataSource;

        int progreso = 0;

        foreach (DataRow row in dta.Rows)
        {
            var dato = dta1.AsEnumerable().Where(c => c.Field<string>("Referencia") == row["Transaccion"].ToString()).FirstOrDefault();

            if (dato == null)
            {
                archivo.GuardarDeposito(idcuenta, row["Descripcion"].ToString(), double.Parse(row["Monto"].ToString()),
                    row["Referencia"].ToString());                    
            }               

            progreso++;
            backgroundWorker3.ReportProgress(progreso);
        }