Limited number of columns in Custom Report (1.9)

Question

I've successfully managed to create a custom report module in Magento following the (sort of) guide here Creating new completely custom reports

I have tried to add 6 columns to the report but it seems to be limited somewhere to only display 4 (both on the front end and csv export). If I remove some columns, the other ones show so they have been created corretly. Here's my grid;

class Juicy_Taxreport_Block_Adminhtml_Taxreport_Grid extends Mage_Adminhtml_Block_Report_Grid
{

    public function __construct() {
        parent::__construct();
        $this->setId('taxreportGrid');
        $this->setDefaultSort('created_at');
        $this->setDefaultDir('ASC');
        $this->setSaveParametersInSession(true);
        $this->setSubReportSize(false);
    }

    protected function _prepareCollection() {
        parent::_prepareCollection();
        $this->getCollection()->initReport('taxreport/taxreport');
        return $this;
    }

    protected function _prepareColumns() {
        $this->addColumn('ordered_qty', array(
            'header'    =>Mage::helper('reports')->__('Quantity Ordered'),
            'align'     =>'right',
            'index'     =>'qty_ordered'
        ));
        $this->addColumn('item_id', array(
            'header' => Mage::helper('taxreport')->__('Item ID'),
            'align' => 'right',
            'index' => 'item_id'
        ));
        $this->addColumn('store_id', array(
            'header' => Mage::helper('taxreport')->__('Price'),
            'align' => 'right',
            'index' => 'base_original_price'
        ));
        $this->addColumn('store_id', array(
            'header' => Mage::helper('taxreport')->__('Tax Percent'),
            'align' => 'right',
            'index' => 'base_original_price'
        ));
        $this->addColumn('store_id', array(
            'header' => Mage::helper('taxreport')->__('Tax Amount'),
            'align' => 'right',
            'index' => 'tax_amount'
        ));
        $this->addColumn('store_id', array(
            'header' => Mage::helper('taxreport')->__('Tax Amount'),
            'align' => 'right',
            'index' => 'tax_amount'
        ));
        $this->addExportType('*/*/exportCsv', Mage::helper('taxreport')->__('CSV'));
        $this->addExportType('*/*/exportXml', Mage::helper('taxreport')->__('XML'));
        return parent::_prepareColumns();
    }

    public function getRowUrl($row) {
        return false;
    }

    public function getReport($from, $to) {
        if ($from == '') {
            $from = $this->getFilter('report_from');
        }
        if ($to == '') {
            $to = $this->getFilter('report_to');
        }


        return $this->getCollection()->getReport($from, $to);
    }
}

In the example above, I can only see one of the tax related columns. If I remove, for example, the quantity column then I see two tax related columns. I have tried sifting through the extended classes but I can't seem to find anything there.

Answer 1

Don't repeated store_id. You can created render for that.

$this->addColumn('store_id_1', array(
    'header' => Mage::helper('taxreport')->__('Price'),
    'align' => 'right',
    'index' => 'base_original_price'
));

$this->addColumn('store_id_2', array(
    'header' => Mage::helper('taxreport')->__('Tax Percent'),
    'align' => 'right',
    'index' => 'base_original_price'
));

$this->addColumn('store_id_3', array(
    'header' => Mage::helper('taxreport')->__('Tax Amount'),
    'align' => 'right',
    'index' => 'tax_amount'
));

$this->addColumn('store_id_4', array(
    'header' => Mage::helper('taxreport')->__('Tax Amount'),
    'align' => 'right',
    'index' => 'tax_amount'
));

like used custom