Which way up do the batteries of a Renault clio 1999 key fob go?

I have read numerous threads on here and understand the procedure of opening the key fob, purchasing two new CR2016 batteries and holding the inside central locking button for ten seconds so it opens and closes. Then pointing the fob at the black sensor next to the rear view mirror. I tried all of this and the key fob did not light up (red bulb). SO i assume that i had put the batteries in the wrong way round. Can anyone help me?