What setting did you give the frown morph? Also smile morphs can be used in reverse. Practically any morph can be used with negative values for an opposite effect.

Another thing is I think it's a sort of optical illusion going on here. As far as I can see, the corners of the mouth ARE horizontal, but his soft and ...er... kissable... amor bow on the lips makes it look like he's smiling when he's really not. 

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You just can't put the words "Poserites" and "happy" in the same sentence - didn't you know that? LaurieA
  Using Poser since 2002. Currently at Version 11.1 - Win 10.