Can't Create PO ,because error message "NO delivery type defined for supplying plant 300 and document." so, I can remove the plant 3000 from below method.
1. From Menu:Environment---->Vendor
2.From Menu,Goto--->Purchasing org. data--->Purchasing data
3.From menu, Extras--->add. Purchasing data
4. Remove the Plant 3000 information. check the following screen shot.