New to Java

Hi, I'm having a weird problem using the invoke method of the Method class.

I've just been playing around with it to understand how to use it and I keep getting this error:

java.lang.IllegalArgumentException: object is not an instance of declaring class

Can someone please tell what's wrong with my code? It's a very simple test but it's generating that exception.

public class Human {

	public void printHeight(Integer height){
		System.out.println("Height is\t"+height);
	}
	public void printWeight(Integer weight){
		System.out.println("Weight is\t"+weight);
	}
	public void printName(String name){
		System.out.println("Name is\t"+name);
	}
	public void printSkill(String skill){
		System.out.println("Skill is\t"+skill);
	}
}

public class MethodInvoke {

	public void callMethodsCreateHuman(Map<String, Object> map){
		//Gets all the methods of the Human class and stores them into an array
		Method[] methods = Human.class.getMethods();
		
		//Adds methods to a map, of method name and method
		Map<String, Method> methodMap = new HashMap<String, Method>();
		for (Method mtd : methods) {
			methodMap.put(mtd.getName(), mtd);
			System.out.println("Method Added\t"+mtd.getName());
		}
		for (String key : map.keySet()) {
			
			//Gets the correct setter method of Human class
			//print + Name = printName
			//print + Weight = printWeight
			//print + Skill = printSkill
			//print + Height = printHeight
			String methodName = "print" + key;

			//Gets the correct method to invoke by looking in the method
			//map created above for its name
			final Method method = methodMap.get(methodName);

			//Gets the actual "Method" object
			Object value = map.get(key);
			
			if(value instanceof String){
				int a = 10;
			}

			//Invokes the methods:
			//Note: The method invoke will call the method with
			//any specified number of parameters but of course
			//the must match the actual number of parameters that
			//method takes. if the method had 5 parameters then you
			//could call put 5 arguments instead of 2 as done below
			try {
				method.invoke(value);
			} catch (IllegalArgumentException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (IllegalAccessException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (InvocationTargetException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}

	public static void main(String[] args){
		Map<String, Object> kimmyMap = new HashMap<String, Object>();
		kimmyMap.put("Name", "Kimba");
		kimmyMap.put("Weight", 40);
		kimmyMap.put("Height", 150);
		kimmyMap.put("Skill", "CIA Intelligence Agent");
		MethodInvoke mi = new MethodInvoke();
		mi.callMethodsCreateHuman(kimmyMap);
	}
}

Thanks heaps,
Newbie