HP ePrint with HP LaserJet 4000 Series PCL6 Problems

I have an old HP LaserJet 4000 Series PCL6 printer that runs on a network. All my other computers can find the printer with ease. I downloaded the HP ePrint on both an iPhone and Samsung Galaxy S4, but the app cannot find the printer on either phone. Does HP ePrint not work with HP LaserJet 4000 Series PCL6 ? I don't know why it won't find the printer. Both the phone and the computer that the printer is hooked up to are on the same network.