Technically your Camaro's smog check was due last April. If we understand correctly... you tried registering your Camaro in April 2011 but did not complete the registration because it failed the smog check. If this is true, your Camaro will need a smog check every year until it passes the smog check, and the initial registration process (or the one in April 2011) is completed.
posted by SmogTips Support