irrevocable purchase

According to the "MOU", the first months order of bird flu test kits for march was a irrevocable purchase order, ie "that cannot be revoked, recalled, or undone; unalterable".
So if that was the case, why did RBY not make them pay up for the first order that was agreed to then cancel the remaining orders, and WHY did it take them 3 months to tell the market that a unidentified source(they wont say which country it was)could not or would not pay up. Or was it RBY that could not make the order, makes me squirm a bit, they need to release more info on this deal, that is if it was a ridgy didge agreement in the first palce, this is just my opinion.