Sales Orders being disregarded by MRP Supply Planning Workbench

Hello everyone,

I have just enabled MRP on my account and I have some strange behaviour that I need to understand.

The items is Item A with a lead time of 5 days. There are 3 instock. These three items are committed to 2 Sales Orders created before I enabled MRP. According to the Estimated Ship Date these two Sales Orders are late.

The Supply plane is considering actual demand only.

I have created a new Sales Order which is required on 10/02. This SO was created after I enabled MRP. The problem comes when I run the supply plan, the supply plan says that there is a Qty of 3 available and pegged one of these 3 to the new SO. If I look at the the demand, it says the only demand for this item is the SO created after MRP was enabled. It appears as though it is ignoring the older two SO’s. Why is this happening.

I have checked the obvious things, like

• The SO’s are for the same location
• The date of the supply plan horizons
• The lines are open on the old SO’s

Can anyone offer any insight to this?