How to compare delivery date in schedule lines and PGI in outbound delivery

Hi,

I want to create a report to monitor and compare different dates in sales and delivery process.

One of my key figure is the comparison between date confirmed to the customer, that I can find in the schedule line of the sales order, and the actual goods issue date from the outbound delivery.

But I can't succeed in making the link between delivery and schedule lines, means between LIKP and VBEP.

Would you have any idea?

Thank you.