Showing error messages.

I hve written validations to check the incoming data. Also in the view i am saying:
<%= error_messages_for “model_name_here” %>.
Now when i am trying to insert invalid data, it is not getting stored in the model(which is gud) but it is not ahowing any error messages on the view rendered…

How can i show these error messages? Plz help.
Thx and regards,