Multi User Access restrictions

Hi Can anyone help - trying to set up multi user access restrictions I want to set up limited access in my warehouse that is to allow my warehouse staff to receive goods in but I do not want them to be able to place purchase orders or view how much the company owes its suppliers!!

Under company/ set up users  Page 2  (Purchases and accounts payable) allows me to give no access to anyhthing to do with purchases. However when I get to page 4 (Stock) I have to allow my warehouse staff to make purchases so that they have access to bring in stock - why is this as I have already sekected no access to suppliers and purchase orders on page 2! Is this an error in the software??