.LUA: Trouble with nil value

[Organized_Chaos]

Hello everyone.. As you can probably tell I am new at LUA programing. I followed all the directions in this tutorial at http://www.evilmana.com/tutorials/lua_tutorial_03.php and I am having problems. How do I make this error go away and make my "program" work?
I get an error message that says
"Error: Variable Tut.LUA:18: attempt to perform arithmetic on global 'myBirthYear' (a nil value)
Press start to restart"
("Variable Tut.LUA" is my file name.)
-
Here is my code:

-- NOTES
-- Green Color Object
green = Color.new(0, 255, 0)

-- Store birth year in variable myBirthYear
myBirthyear = 1991

-- Store current year in currentYear
currentYear = 2008

-- create an empty variable
myAge = nil

-- Store some text in a variable (Note the 

space after the last word before the end ")
someText = "My age is roughly "

-- Subtract myBirthYear from currentYear 

and store in myAge
myAge = currentYear - myBirthYear

-- Print our text variable to the screen 

(NOTE that there are no "" surrounding 

someText)
screen:print(10,100,someText .. 

myAge,green)

-- Buffer offscreen to onscreen (If this 

was a human, offscreen would be thinking 

about it, onscreen would be saying it)
screen.flip()
-- Loop forever
while true do
screen.waitVblankStart()
end

The only thing I did differently was use my birth year and the current year instead of the years in this tutorial. And I added a few custom notes using the "-- text" format. Since this was a tutorial I figured I might add in a few things in case I use this file later as a reference or something. That stuff shouldn't make a difference should it?

[hotrocker]

we have a lua section ;)

[Organized_Chaos]

Yes I see that. Sorry :)

[hotrocker]

repost it over there for now and this one'l get deleted next time a mod is on

[RazorChrist]

Chaos, here's part, if not all, of the problem...look at your math, versus how your variable is setup:

-- Store birth year in variable myBirthYear
myBirthyear = 1991

and store in myAge
myAge = currentYear - myBirthYear

Notice that when you setup your variable, it's spelled "myBirthyear" with a lower case Y in year....but in your math, you have an upper case Y. Try changing the Y in your variable setup to an upper-case Y and see if that fixes the issue. Case-sensitive is a bitch sometimes.

[Organized_Chaos]

Damn, can't believe I missed that. I knew everything was case sensitive.. I just over looked that.
Thanks I changed that and it worked fine.

[Blade_punk]

Il move just so anyone else who visits the LUA Section with the same error can find this

[RazorChrist]

Haha, yeah I miss stupid crap like that all the time till I start getting errors on compile/runtime. You just have to go all the way back through, line by line, usually looking for a missing equals sign or semi colon.

[Organized_Chaos]

Is C or C++ coding case sensitive like this? Are all programing languages like that? I am use to HTML where most of the time everything is either all lowercase or all uppercase. HTML is the only code I am somewhat use to writing.. But I'm no expert on it either.

[RazorChrist]

Not sure about "most" but usually unless it's a web-based scripting, it's usually case sensative. I know C++ and C are for sure.