That's what I do and with the RLS I have found as well as pulling the tile.off slightly, it opens the joint, even though the wedge should be pulling it down to the fixed tiles, I find it strange?Push the wedge in towards the already fixed tiles and it won't open the joint up..
And while we're on the subject anything more than 4pence a clip for a little chunk of non biodegradable plastic is expensive imo..