Because the company has been very careful to use the word "shipment" and not "order." It's too bad that they won't be transparent enough to let shareholders know clearly.
However, since they never avoid tooting their horn, you can also draw a conclusion that since they announced at the SHM that they were only going to order 1,000 units, that had they sold all 1,000 units they would have made that clear when they said they sold out the first "shipment." RP also stated that they were shipping them in smaller quantities to get through customs faster.
It's possible that the numbers given to SGE were wrong or that the first shipment was larger than subsequent shipments. However, I do not believe there is any reason to believe that the first shipment was for the entire order of 1,000 units.
