Multisite, Global cart, Delete product problem

Hi,
I am using Marketpress 2.3.1. on a multisite installation. My problem is : when i delete a product from the cart, it does not always work well. After searching for a bit, i realized this had something to do with my "current blog id". The reason i say that is that is this one :
- i have 2 products in the cart, from different vendors
- i try deleting them both
- only one is deleted
- to be able to delete the other one, i have to go into the remaining product's corresponding blog and then delete it from the cart and it works

Have any clue ?
Thanks !
Cyprien