Annexin staining with platelets

I have a question concerning staining of platelets with annexin V and PI.  I used a kit from Pharmagen to stain 8 day old platelets and 
very few cells stained with PI.  Since I haven't done this type of staining with platelets I don't know what to exspect.  I did see quite 
a few cells that were Annexin V positive but not PI positive.  If anyone has done some staining on platelets with Annexin V and PI  I 
would appreciate any information.  
Thank you, Jim Kurtz