Kay, you should start by reviewing the menu for Stock - Inquiries. There is an Allocation section with 'Stock shortages' (Function: CONSSMQ). This will have the quantities that were not available to be allocated. However, if you want to see a list of orders that have not been allocated, see if the 'Projected stock' inquiry has what you need. 

It could be your requirement is specific to your process and in this case, you can review the graphical query tools and see if you find a query that you can modify to suit your data needs. These can also be added to dashboards. This topic is beyond the scope of a community board. You can explore this with your Sage partner or your local support team can review the functionality of these query tools. Support will not build queries for you, however, we can provide direction on where data is stored in the Schema (SQL tables).