private void ipAddressEntered(){
		String ip = txtIpAddress.getText();
		
		if(!ip.equalsIgnoreCase("Enter IP Address")){
			if(!IPV4Address.validateDecIP(ip)){
				lblError.setText("Invalid IP Address");
				lblError.setForeground(Color.RED);
				lblError.setVisible(true);
				controller.shakeDiaLog(this);
				ErrorFlag = true;
			}else{
				lblError.setVisible(false);
				IPAddress = ip;
                                if(txtSubnetMask.getText().equals("Enter Subnet Mask") || txtSubnetMask.getText() == null || txtSubnetMask.getText().equals("0.0.0.0")){
                                    SubnetMask = IPV4Address.getDefaultSubnetMask(IPAddress);
                                    txtSubnetMask.setText(SubnetMask);
                                    txtSubnetMask.setEnabled(true);			
                                }
				ErrorFlag = false;			
			}		
		}		
	}