Sql Server replication: Initial snapshot for publication is not yet available?

I had setup transactional replication and my distributor, publisher are on same windows server and 2 subscriber one on same server and another on other windows server both using push snapshot. I am getting the message in the synchronization status, that snapshot is not yet available, just a few hours back it was working fine every transaction was synchronized. The only thing i did in between was, added more articles(stored procedures, etc.) to the publication using its properties. Is it causing the issue here, there is no error message displayed. Just that I am not able to get the data replicated