Error when image-magick toolkit is enabled.

Unable to upload any images. Works fine in GD2. /usr/bin/convert is the correct path according to site host.

Version: ImageMagick 6.4.3 2008-10-13 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2008 ImageMagick Studio LLC

Error:

ImageMagick command: /usr/bin/convert -resize 100x39! 'sites/default/files/images/temp/FWD 26x26 LWB.jpg' 'sites/default/files/images/temp/FWD 26x26 LWB.thumbnail.jpg'
ImageMagick output:
Unable to create scaled Thumbnail image.

Thanks...