In reply to dave_59:
Dave, thank you very much for suggestions and details, it makes sense now.
Sorry I forgot to code tag, and also forgot to mention it is synchronous signal.
If synchronous, you should only be using the clk edge and not wait statements.
Dave , can you please elaborate on this. I was in the impression that I can use wait wherever I want to wait for any signal or any variable conditions?
I am going to do few more experiments to further confirm if I have any question left for your valuable inputs.