ALV grouping with Checkbox

Hi,

I have an ALV report with chcekbox and PO item detials. Now the checkbox appears for each line item of the PO.

We have to group the report for the PO Number and checkbox should appear one per PO number-common for all the line items under 1 PO.

Not sure why but the grouping functionality of the ALV is lost with checkbox. Is there any workaround for this.

Appreciate ur ideas.

Regards,