I think its depends what spray you use sometimes wrong code to the spray you want to use on left4dead
I wasn't able to use sprays until about 6k points. I would imagine the server has to add you to whatever spray whitelist exists and it probably doesn't do that daily considering how slow points gain is for new players
Sometimes rejoining the server will help with the issue but it can depend I think, once I finally hit 5k points I was able to spray but I had to rejoin or join another core-ss server.