Timer1 not recognized during compile

I have downloaded the latest TimerOne.h library file from here. Arduino Playground - HomePage . Put it in the library directory where I extracted my latest version of Arduino 1.0.4 and I am getting a verify error of Timer1 not declared in scope. I am using the example code that came with the download for blinking an LED. I am using the Mega 2560. Can someone please help. Here is the example code.

#include <TimerOne.h>

void setup()
{
// Initialize the digital pin as an output.
// Pin 13 has an LED connected on most Arduino boards
pinMode(13, OUTPUT);

Timer1.initialize(100000); // set a timer of length 100000 microseconds (or 0.1 sec - or 10Hz => the led will blink 5 times, 5 cycles of on-and-off, per second)
Timer1.attachInterrupt( timerIsr ); // attach the service routine here
}

void loop()
{
// Main code loop
// TODO: Put your regular (non-ISR) logic here
}

/// --------------------------
/// Custom ISR Timer Routine
/// --------------------------
void timerIsr()
{
// Toggle LED
digitalWrite( 13, digitalRead( 13 ) ^ 1 );
}

Are you getting any other error, like "TimerOne.h not found"?

Did you remember to re-start the IDE after installing the library?