Do you have a IR thermometer you could point at the plates and check the temp? Or maybe lightly squeeze the probe from an instant read meat probe style between them to double check the temp on the plates. My gut instinct from the pics of the pressed flower is that maybe the temp isn't up there. There's really only the two components of the process... pressure and heat. The number I've read for minimum temp is around 150F, but personally I'm starting to like the 250-275 range. Haven't tried anything under 225. The chips in the pic look like there's decent pressure. More the merrier with that, though, so crank down on 'em as hard as the press will allow.
Here's an example pic of what I mean by using a kitchen style thermometer to check the temps of the plates...
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