Java:Exception in thread "main" java.lang.Exc

Bonjour,
prg suivant donne erreur "exception", veuillez m'aider svp

public class Student  
{ 
 int rollNumber; 
 void getNumber(int n) 
 { 
  rollNumber=n; 
 } 
 void putNumber() 
 { 
  System.out.println("Roll No:"=rollNumber); 
 } 
} 
class Test extends Student 
{ 
 float part1,part2; 
 void getMarks(float m1,float m2) 
 { 
  part1=m1; 
  part2=m2; 
 } 
 void putMarks() 
 { 
  System.out.println("Marks obtained"); 
  System.out.println("Part1="+part1); 
  System.out.println("Part2="+part2); 
 } 
} 
interface Sports 
{ 
  float sportWt=6.0F; 
  void putwt(); 
} 
class Results extends Test implements Sports 
{ 
 float total; 
 public void putWt() 
 { 
  System.out.println("Sports Wt="+sportWt); 
 } 
 void display() 
 { 
  total=part1+part2+sportWt; 
  putNumber(); 
  putMarks(); 
  putWt(); 
  System.out.println("Total score="+total); 
 } 
} 
class Hybrid 
{ 
 public static void main (String []args) 
 { 
  Results Student1=new Results(); 
  Student1.getNumber(1234); 
  Student1.getMarks(27.5F, 33.0F); 
  Student1.display(); 
 } 
} 

j'ai erreur suivante
Exception in thread "main" java.lang.ExceptionInInitializerError
at javaapplication1.Hybrid.main(Student.java:54)
Caused by: java.lang.RuntimeException: Uncompilable source code - javaapplication1.Results is not abstract and does not override abstract method putwt() in javaapplication1.Sports
at javaapplication1.Results.<clinit>(Student.java:34)

ligne 54 est:
Results Student1=new Results();
ligne 34 est:
class Results extends Test implements Sports