The problem using the built in flash is that it only faces forward and, outdoors, will be hit and miss to communicate with the remote.
When I have used CLS in sunny conditions I have placed a SB800 as master on the camera pointing at the remote unit. Also, to improve signal reception, a small piece of card bent to shade the little IR window from the sun can be fixed to the remote with tape or presstik.
Of course the remote should be rotated to face the IR window at the master flash.
Regards, Clive Liddell Pietermaritzburg South Africa