New to Java

I'm new to Java and am having trouble with a "method not visible" error when trying to use a package by another person (which works in its own context.) As far as I can tell all the relevant classes and methods should be public and accessible.

Here is the basic form of the code I'm trying to make use of:

package org.p2c2e.zag;

public final class Zag {
	public void start() {
           ...
	}
}

And here is my stripped down code. The z.start() line produces the error message "The method start() from the type Zag is not visible."

import org.p2c2e.zag.*;

public class BasicTest {
  public static boolean simpleOpen(File fi) {
     Zag z = new Zag(fi, iStart);
     z.start();
  }
}

The Zag class and the start() method within it are both public. Am I missing a general concept here or is something up with the rest of the code?

Thanks in advance,

--Aaron