I found out why the T: was not working ( or not displaying text on the other side )
I notice the data was sent over to the receiving end but was NOT displayed on the serial monitor...
Just to make the instruction much more clearly :-
To send a text to the other side to be displayed by serial monitor, you will need to type in :-
"T:S:print this text"
so that the other side will see :-
"S:print this text"
... and the if statement matching "S:" will sent it to the Serial.print function displaying
"print this text"