Junit method not found

I'm trying to build a sample test class using junit framework.
I've downloaded junit4.9b3.
When I try to complie my test class I get the following error:-

javac -cp ".;C:\Documents and Settings\user\Desktop\junit\junit4.9b3\junit-4.9b3.jar"     
TestSubscription.java    
TestSubscription.java:10: cannot find symbol    
symbol  : method assertTrue(boolean)    
location: class TestSubscription    
            assertTrue(s.pricePerMonth()==100.0);        
            ^
TestSubscription.java:17: cannot find symbol    
symbol  : method assertTrue(boolean)    
location: class TestSubscription    
            assertTrue(s.pricePerMonth()==66.67);
            ^
2 errors

Looks like assertTrue is not available but the junit javadoc mentions this method.
I'm using the import as follows

import org.junit.*;     
import org.junit.Assert.*;

Any ideas?