Your browser is probably set to NOT print background images. Simply click "file", then click on "page setup". Then check the box for "print background images". Your certificate should now print the signature correctly.
If your browser cannot print background images there are two other ways to capture the signature correctly. If you have Windows Vista or Windows 7 the easiest way is to use the "Windows Snipping Tool" located in the accessories program folder. Simply click and drag a window around the certificate and a cropped screen shot will be captured. Then click, "save as" and you'll have a fully printable certificate saved as a photo.
The second method is to
1) Open up a photo editing program such as Windows Paint.
2) On your screen position the certificate so that you can see it all on your screen.
3) Press the "Prt Sc" or "Print Screen" button on your keyboard.
4) Open the window for the photo editing program you are using and paste the screen shot.
5) Crop the certificate image from the larger picture you captured. If using window paint this requires you to click on crop, then click and drag the cropping box around your certificate, and then click on crop a second time.
6) Save the file to your computer. You can print anytime.