Purchase order created with different company code

Hi,

We are able to create a Purchase order with a differnt company code than the one assigned to the plant as follows:

Plant 1000 assigned to Company code 1001

Plant 1200 assigned to Company code 1201

Still PO got created with plant 1000 in line item and company code 1201 in the header..

There is only one Purchase organization 1000 which is not assigned to any Company code (means it is applicable to both company codes).

Both plants are assigned to the purchase organization 1000.

Please advise .

Regards,

Pratap