I don't think you have the bumps turned up far enough. Turn it up more. Look at the solid growth tree bump map and see what it's settings are. Try the same settings and then try turning that up more if it's not working properly. You could also save the solid growth bump and use it on your other bark. I found I had to turn up the bumps lots to get it to look real with mapped pictures. You also need a bit of highlight to get bar to look perfect. I use the same pattern as the bump for that in the highlight section of the material editor. Make sure you also have the scale of the bump proper. It looks like you have it turned up to much. make sure the gain number is the same, that's important. It makes the biggest difference on bumps. Oh one more thing to check if you made the tree trunk double click on it's name and turn off smoothing.