Change Base unit of measure

Hi Experts,

Greetings to all...

I wish to ask following question (I tried searching for this issue in the forum but couldnt find anything on this):

I am trying to change the Base unit of measure of one of the material. The stock of material does not exist in any of the plant and all the previous stock is consumed. But the system is not allowing me to change the unit of measure. When i looked at the error it shows me the list of the reservation and PO. Where as the goods was issued for the reservation and the PO was received.

In one of the thread of the forum i saw that the system checks for the deletion indicator of PO and Reservation. But in my case the PO and reservation both were completed.

Please suggest if I have missed anything or anything else can be done in this regard.

Thanking you in advance,

Regards,

UK.