Como recorrer un DataSource Dynamics ax 2012?

public Amount valAmounLine(  )
{
    //Este metodo regresa un monto de una serie de lineas recorriendo directamente el DS.
    FormDataSource      form_ds;
    Common              common;
    ;

    AJMUDLine.write();

    form_ds = AJMUDLine_ds;//DataSource del formulario

    amountLine = 0;

    for ( common = form_ds.getFirst(); common ; common = form_ds.getNext() )
    {
        sumAJMUDLine = common;

        if ( !sumAJMUDLine.Amount )
        {
            amountLine += LinesGrid_Amount.realValue();
        }
        else if( LinesGrid_Amount.realValue() )
        {
            if ( sumAJMUDLine.Amount != LinesGrid_Amount.realValue() )
            {
                 amountLine += LinesGrid_Amount.realValue();
            }
            else
            {
                amountLine += sumAJMUDLine.Amount;
            }
        }
        else
        {
            amountLine += sumAJMUDLine.Amount;
        }
    }
    return amountLine;
}