VERIFIED SOLUTION i
Content Author allows to create messages which can be associated with condition. These messages are then used in Designer. After applying the condition, message environment was imported and HIM was generated. Upon performing the Advance Preview, messages did not appear.
When the variables are declared in content author with a certain condition, they have to be mapped to data variables in Designer.
So since there was no linking between variables defined in Content Author and Designer, condition failed as there was no value substituted.
ResolutionUPDATED: September 14, 2017
Choose to set Action Variable and browse to "Message tab" . Choose the variable to be mapped and then map it to the required system or data variable.
After the required are mapped, messages appear in Advance Preview.