a renderer problem - Java-Gaming.org

I am having a problem. I am just starting to play around with jogl. I created a filled polygon which represents a wall and created a camera using the glu.gluLookAt, but when I move my location close to this polygon, I get this huge black area that goes through the polygon. Why do I get that? Can someone run my code and see if they know why I am getting this black area running through the object that I don't think should be there? I don't know if it is my code or jogl.

*****************one class*******************
import net.java.games.jogl.*;
import javax.swing.event.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.event.*;
import javax.swing.JOptionPane;
import javax.swing.event.*;
import java.util.Random;

public class LabrynthFrame extends JFrame implements GLEventListener,KeyEventDispatcher
{
private int width=1030;
private int height=900;
private Labrynth labrynth=null;
private GLCanvas canvas=null;
   private double eyex=0.0;
private double eyey=0.0;
private double eyez=4.5;
private double centerx=0.0;
private double centery=0.5;
private double centerz=-100;
private double upx=0.0;
private double upy=1.0;
private double upz=0.0;
private double heading=270;

public LabrynthFrame()
{
setTitle("The Labrynth");
setSize(width,height);

GLCapabilities capabilities = new GLCapabilities();
canvas=GLDrawableFactory.getFactory().createGLCanvas(capabilities);
canvas.addGLEventListener(this);

this.getContentPane().add(canvas);

labrynth=new Labrynth();

   setLocation(0,0); //the default location
   KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(this);
this.setVisible(true);

setDefaultCloseOperation(EXIT_ON_CLOSE);

Animator animator=new Animator(canvas);
animator.start();

}

public void init (GLDrawable drawable)
{

GL gl = drawable.getGL();
GLU glu=drawable.getGLU();

gl.glShadeModel(GL.GL_SMOOTH);
gl.glEnable(GL.GL_DEPTH_TEST);

gl.glClearColor((float)0.0,(float)0.0,(float)0.0,(float)0.0);

gl.glViewport(0,0,width,height);
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glLoadIdentity();
glu.gluPerspective((float)52.0,(float)width/(float)height,(float)1.0,(float)1000.0);
gl.glMatrixMode(GL.GL_MODELVIEW);
gl.glLoadIdentity();

}

public void display (GLDrawable drawable)
   {
GL gl = drawable.getGL();
GLU glu=drawable.getGLU();

gl.glClear(GL.GL_COLOR_BUFFER_BIT|GL.GL_DEPTH_BUFFER_BIT);

gl.glMatrixMode(GL.GL_MODELVIEW);

gl.glPushMatrix();

gl.glLoadIdentity();

glu.gluLookAt(eyex,eyey,eyez,centerx,centery,centerz,upx,upy,upz);

   labrynth.draw(drawable);
   gl.glPopMatrix();

gl.glFlush();

}

public void reshape (GLDrawable drawable, int i, int x, int width, int height)
{
   }
public void displayChanged (GLDrawable drawable, boolean modeChanged, boolean deviceChanged)
{
   }
public boolean dispatchKeyEvent(KeyEvent event)
{
double tempx=0.0;
double tempy=0.0;
double tempz=0.0;

if(event.getID()==KeyEvent.KEY_PRESSED)
{

switch(event.getKeyCode())
   {
   case KeyEvent.VK_LEFT:

heading--;
if(heading<0)
heading=360;
if(heading>360)
heading=0;

centerx=((Math.cos(Math.toRadians(heading)))*(100+eyex) );
centerz=( (Math.sin(Math.toRadians(heading)))*(100+eyez) );

break;

case KeyEvent.VK_RIGHT:

heading++;

if(heading<0)
heading=360;
if(heading>360)
heading=0;

centerx=((Math.cos(Math.toRadians(heading)))*(100+eyex) );
centerz=( (Math.sin(Math.toRadians(heading)))*(100+eyez) );

break;

case KeyEvent.VK_UP:

tempx=eyex;
tempz=eyez;
tempx+=(Math.cos(Math.toRadians(heading)));
tempz+=(Math.sin(Math.toRadians(heading)));

   eyex=tempx;
eyez=tempz;
}

break;

case KeyEvent.VK_DOWN:

tempx=eyex;
tempz=eyez;

tempx-=(Math.cos(Math.toRadians(heading)));
tempz-=(Math.sin(Math.toRadians(heading)));

if(!labrynth.collision(tempx,tempy,tempz))
{
eyex=tempx;
eyez=tempz;
}

break;

default: break;

}//end switch statement

}//end event.getId

return false; //doesn't pass key pressed on to other listeners if true

}//end dispatch event key

}//end of LabrynthFrame class
//***********************2nd class*****
//The Labrynth game, this class contains the Dungeon
//Created by Greg Dias

import net.java.games.jogl.*;

public class Labrynth
{
   public Labrynth()
{

   }//end Labrynth constructor

public void draw(GLDrawable drawable)
{

GL gl = drawable.getGL();
   (GL.GL_FRONT_AND_BACK,GL.GL_FILL);

gl.glBegin(gl.GL_POLYGON);

gl.glColor3f((float).5,(float)0,(float)0);
gl.glVertex3f((float)0,(float).5,(float).5); //top right point
gl.glVertex3f((float)-3.5,(float).5,(float).5); //left point
gl.glVertex3f((float)-3.5,(float).5,(float)3.5);//top front point
gl.glVertex3f((float)-3.5,(float)-.5,(float)3.5);//bottom front point
gl.glVertex3f((float)-3.5,(float)-.5,(float).5);//bottom back point
gl.glVertex3f((float)0,(float)-.5,(float).5);

gl.glEnd();
   }

}//end Labrynth class