Brand-new photopolymer stamps need a little TLC before they hit the Whisper White for the first time. Don't panic, it's not a big deal, but you will save a lot of cardstock if you take the time to do this little trick. Ink up your stamp in a light color and stamp it 2-3 times on scrap cardstock then clean it using your Stampin' Scrub & Stampin' Mist cleaner. Repeat until you are getting a clean, solid stamped image. That's all that's needed. Here's a great video from Jennifer McGuire that explains a different approach - either one will work great for you.
Enjoy this tip, I hope it saves some frustration for you!