Sales Orders have Quantity Ordered, Quantity Shipped and Quantity Backordered.  Once you invoice off that sales order, and if you invoice the line complete, that line is removed from Sales Order Entry (as you explained above, line one is gone).  However, Line two (now the first line); shows 100 ordered and 100 backordered.  And Line Three (now the second line); shows 150 ordered, 50 shipped and 100 backordered.  In Item Maintenance the SO Quantity is zero and the "on Back Order" Quantity is 200.  Your printed Sales Order is customizable in Crystal reports.  Try creating a fresh form (default); and  it should show you all three elements.  On Order, Shipped Previously, and On Backorder.  Your form may be customized and someone choose to just print "Original Order Quantity" not the current remaining quantity to ship.

Thanks, but  I was worried that was the reason.  I found the field in the crystal report and there is a formula tied to the field.  Would I be correct in adjusting the formula to show the backordered quantity if the shipped qty does not equal the original ordered qty?

Yes, that is what you want.  On order lines with BO = 0, then Ordered less Shipped.  On orders with BO <> 0, then the BO Quantity.  

Ok, I used the suppress field function to suppress the field if the certain criteria was meet and it worked.  I couldn't figure out how to make the actual field a formula.