I’m afraid that did nothing for me either.
…and, er, isn’t this simpler? (granted, without the flexibity of having RESTORE as a possibility)
When play begins:
say "Restore a saved game (Y/N)?[run paragraph on] ";
if player consents:
try restoring the game;
else:
say "Welcome, then!";
I’ve seen quite a few games ask both questions, tell you the truth. First they ask, do you want to restore? Then they ask, do you want to see the intro? This is usually good enough.
…actually, it’d be even easier to use a Title Page extension.
EDIT - I adapted Identity Theft (an Inform example). I think this’ll do what you want.
[code]Place is a room.
Instead of looking when intro: do nothing.
Rule for printing the banner text when intro: do nothing.
Rule for constructing the status line when intro: do nothing.
When play begins:
now the command prompt is "See the intro (Y/N) or restore a saved game? ".
To decide whether intro:
if the command prompt is "See the intro (Y/N) or restore a saved game? ", yes;
no.
After reading a command when intro:
now the command prompt is “>”;
if the player’s command includes “yes/y”:
say “INTRO. There, you’ve seen it.”;
otherwise if the player’s command includes “restore/load”:
try restoring the game;
otherwise if the player’s command includes “no/n”:
say “Ok, then, here’s the game.”;
otherwise:
say “I don’t think that was one of the options, was it? Naughty naughty.”;
now the command prompt is "See the intro (Y/N) or restore a saved game? ";
reject the player’s command;
say line break;
say banner text;
move the player to starting room;
reject the player’s command.
Starting room is a room. “This is where it starts. Exciting, isn’t it.”[/code]
If in doubt, this is what you’ll want to do - find an example that does what you want, sort of, and tweak it until you get what you’re looking for. 
Note I was a bit free with my text-matching. If the player types “Oh yes I most certainly wish to see the intro”, it’ll be treated as a yes. If the player is a smart-ass and types “Yes I do want to restore n all.” it’ll be considered as “yes”, because that’s the first keyword I checked for.