Strange string constructor compile error

Hi,

I made a class like:

    public class Whatever
    {
        public void Whatever(String str);
    }

I'm using it in some other file like:

    Whatever w = new Whatever("hello");

but the compiler is complaining that it can't find a constructor for Whatever that takes a String. Why would this be happening? I'm using other functions as part of the same / other classes that take a string as a parameter, no problem...

Thanks