Inequalities in Small Basic... Help!?

Ok, I'm writing a program for class that's supposed to take text input from the user (a "guess"), convert that to uppercase (to compare easier) and then decide if the user's input matches the word they're supposed to be guessing (in this case "EUGENE") Everything works fine, except I'm trying to use a while loop to re-prompt and get a new guess if the user inputs anything other than "Eugene" and I can't for the life of me figure out how to write the conditional. I would have thought it would be =! (for does not equal) but that spits an error at me. I can't find any help on the internet, so I'm hoping maybe some smart programming people will be able to tell me what to do.

Alternatively, maybe there's a better way to do this? Aw, heck, here's my code:

GUESS_CORRECT = "EUGENE"

TextWindow.Write("Enter your guess:")

Guess = TextWindow.Read()

Guess = Text.ConvertToUpperCase(Guess)

While (Guess =! GUESS_CORRECT)

TextWindow.WriteLine("Sorry, that's not it")

TextWindow.Write("Enter your guess:")

Guess = TextWindow.Read()

Guess = Text.ConvertToUpperCase(Guess)

EndWhile

If Guess = GUESS_CORRECT Then

TextWindow.Write("You got it!")

EndIf

Seriously, Small Basic is too ridiculously simple or something. Helps?