Can you tell what the problem is?
Well, I went to www.fredrixartistcanvas.com as they directed me to, which redirected me automatically to its 'new' home www.taramaterials.com, not technically a goof, since companies are bought and sold and domains change all the time.
Tara Materials has been the sole owner of Fredrix Artist Canvas since 1968, when Arthur Freidrich sold the NY based canvas manufacturer to a couple of guys from Atlanta.
I recently purchased my second pair of canvas pliers in 33 years because the first ones broke. Can you believe something I bought in college would only last 33 years or so? But way back in college, I learned that to properly stretch a canvas you tack stretched canvas starting in the middle of each bar and work the opposite side for the next tack.
The Fredrix canvas "mounting" instructions, while not very clear, are in agreement with what I was taught about working from the center out and across.
But look at the staples in the illustration.
Yes, I am picking on Fredrix for their packaging, but it is all tongue-in-cheek — I am confident in most any of their products, and as with any manufacturer, they produce varying qualities of some products to suit certain needs.
I am confident that the average artist who only stretches a few dozen canvases a year will do just fine with a set of generic canvas pliers, just as well as another brand for $15 more or, if you want to have exactly what I am using (and they do have some nice additional features, like a wider grip and a grip-handle stop at the far end to, presumably prevent breakage) you might want to go ahead and pony up the extra few bucks to get the Fredrix canvas pliers.