The French, UK and US regimes refused to delay their bombing raid on Syria until the OPCW had made its inspection of the site in Douma where a chemical weapons attack was alleged to have occurred. Not only did the regimes refuse to wait, the OPCW has had a devil of a time getting to the site even after the raid. Today they announced that their reconnaissance team had to withdraw because of gunfire in the town.
Of course every day that passes after the alleged chemical incident makes it harder for the inspectors to find evidence.
Given that the Syrian and Russian governments know full well that they weren't responsible for any chemical attack in Douma, if one took place at all, they've been eager for the OPCW to complete its inspection.
But all that begs the question of why FUKUS didn't hold off a few days until the inspection was done.