I could not get ordering to work until I realised that I had not set the supplier as 'Preferred', so I called up the product in question and in the Suppliers tab, clicked the Preferred box and immediately I get the error shown below. Every time you click the preferred box, you get the error. However, if you OK the error box and then OK the edit screen, all is updated as you want.

 <error-report>
<version>1.7-beta-2-SNAPSHOT</version>
<revision>5541</revision>
<message>org.openvpms.web.component.im.relationship.EntityRelationshipCollectionEditor cannot be cast to org.openvpms.web.component.im.edit.AbstractIMObjectCollectionEditor</message>
<exception>
<type>java.lang.ClassCastException</type>
<message>org.openvpms.web.component.im.relationship.EntityRelationshipCollectionEditor cannot be cast to org.openvpms.web.component.im.edit.AbstractIMObjectCollectionEditor</message>
<stackTrace>
<trace>org.openvpms.web.component.im.product.ProductEditor.onSupplierChanged(ProductEditor.java:86)</trace>
<trace>org.openvpms.web.component.im.product.ProductEditor.access$000(ProductEditor.java:44)</trace>
<trace>org.openvpms.web.component.im.product.ProductEditor$1.modified(ProductEditor.java:76)</trace>
<trace>org.openvpms.web.component.property.ModifiableListeners.notifyListeners(ModifiableListeners.java:92)</trace>
<trace>org.openvpms.web.component.im.edit.AbstractIMObjectCollectionEditor.onModified(AbstractIMObjectCollectionEditor.java:518)</trace>
<trace>org.openvpms.web.component.im.edit.AbstractIMObjectCollectionEditor$1.modified(AbstractIMObjectCollectionEditor.java:128)</trace>
<trace>org.openvpms.web.component.property.ModifiableListeners.notifyListeners(ModifiableListeners.java:92)</trace> 

Regards, Tim G