I probably found your problem if your are using version 0.6
The naming convention has changed in the last version.
In the Tutorial, in the section where you have to insert the procedure, the code is no more up to date.
use this one:
proc HelloWorld
t$ = GetText(MEMO102$);
s$ = t$ + "\n"+ "Hello World !";
SetText(MEMO102$, s$);
end;
As you can see, only the name of the control has changed, so you can aslo only check in your code.
Compare the properties of you control by double-clicking in the control.
The name of the control in selected so you can copy/paste it directly to your code.
Don't forget the $ at the end of the control name.
I'm updating the tutorial, it will be updated asap.