Combining two libraries, first project

I am trying to combine the DHT22 library with the Liquid Crystal library to display Temp and Humidity on a 16,2 LDC display. This is the code I have so far.

// include the library code:
#include <LiquidCrystal.h>
// include DHT lib
#include <DHT22.h>
// connect dht data to pin 7
#define DHT22_PIN 7
// Setup DHT instance
DHT22 myDHT22(DHT22_PIN);


// initialize the lcd library with the numbers of the interface pins
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  // set up the LCD's number of columns and rows: 
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print(" TEMP     HUM");
}


void loop(void)
{ 
  DHT22_ERROR_t errorCode;

  delay(15000);
  errorCode = myDHT22.readData();
  switch(errorCode)
  {
    case DHT_ERROR_NONE:
      lcd.setCursor(2,1);
      lcd.print(myDHT22.getTemperatureC());
      lcd.print("C ");
      lcd.setCursor(10,1);
      lcd.print(myDHT22.getHumidity());
      lcd.println("%");
      break;
    case DHT_ERROR_CHECKSUM:
      lcd.setCursor(2,1);
      lcd.print(myDHT22.getTemperatureC());
      lcd.print("C ");
      lcd.setCursor(6,1);
      lcd.print("SMER");
      lcd.setCursor(10,1);
      lcd.print(myDHT22.getHumidity());
      lcd.println("%");
      break;
    case DHT_BUS_HUNG:
      lcd.setCursor(4,1);
      lcd.println("BUS Hung ");
      break;
    case DHT_ERROR_NOT_PRESENT:
      lcd.setCursor(4,1);
      lcd.println("Not Present ");
      break;
    case DHT_ERROR_ACK_TOO_LONG:
      lcd.setCursor(4,1);
      lcd.println("ACK time out ");
      break;
    case DHT_ERROR_SYNC_TIMEOUT:
      lcd.setCursor(4,1);
      lcd.println("Sync Timeout ");
      break;
    case DHT_ERROR_DATA_TIMEOUT:
      lcd.setCursor(4,1);
      lcd.println("Data Timeout ");
      break;
    case DHT_ERROR_TOOQUICK:
      lcd.setCursor(4,1);
      lcd.println("Polled to quick ");
      break;
  }
}

This is the errors I get
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:47:24: error: WConstants.h: No such file or directory
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp: In constructor ‘DHT22::DHT22(uint8_t)’:
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:64: error: ‘digitalPinToBitMask’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:65: error: ‘digitalPinToPort’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:65: error: ‘portInputRegister’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:66: error: ‘millis’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp: In member function ‘DHT22_ERROR_t DHT22::readData()’:
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:90: error: ‘millis’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:115: error: ‘delayMicroseconds’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:122: error: ‘delayMicroseconds’ was not declared in this scope
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp: In member function ‘void DHT22::clockReset()’:
C:\Users\Documents\Arduino\libraries\DHT22\DHT22.cpp:242: error: ‘millis’ was not declared in this scope

I do not understand what to do to fix these errors. I am guessing it has something with the .cpp however I do not know how to fix it. Any efforts to help me figure this out is greatly appreciated.

WConstants.h: No such file or directory

That means it is an old library and will not work with Arduino IDE version 1.xx You basically have to change the offending file. See this http://makezine.com/2011/12/01/arduino-1-0-is-out-heres-what-you-need-to-know/

or this http://forum.arduino.cc/index.php?topic=85529.0