manual Delivery date change on sales order for weekends

Hi frnds

I have an issue. The delivery date on the sales order when manually changed for weekends(saturday and sunday) is getting determined by the system, though if i select sunday the system proposes material loading date as friday but is picking sunday as delivery date.

Since we have maintained factory calendar for weekdays the system should be proposing the following monday for delivery right??? The factory calendar has been assigned to Plant(OX10), Sales Org(OVX5) and Shipping point(OVXD).

Can someone suggest if i need to maintain additional config so that when the del. date is manually changed to weekend the system should suggest the following Monday as delivery date....

Thanks

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