It appears as though the number of slots available for entry into the Counter-Strike: Source beta were severely limited. At this time if you were unable to opt into the beta, it is unknown whether or not you will be able to get in at all until the beta goes live for everyone.
We have an email in to Valve to perhaps see if they will open up more spots in the future or of this limit is it.
We have an email in to Valve to perhaps see if they will open up more spots in the future or of this limit is it.