Function to valid a column start with "http"

Hi,

I'm looking for a way to validate if the input start with "http".

I have a formula in my validation field that look like this:

=(MINUSCULE(GAUCHE(B2;4))="http")

It's okay for the cell B2... but I need that validation to apply on all the colum. I tried:

=(MINUSCULE(GAUCHE(B:B;4))="http")

But I keep getting an error EVERY time, even if it's valid.

Thanks.

jonat

Edit: As you can see my excel is'nt in english... in english, "minuscule" should be something like "lowercase" and "gauche" mean "left"