When click 'apply' in watermark, the watermark image is not applied.

It works on GD.

Error from Firebug:

An unexpected error has occurred. Please contact the webmaster.<br />Transformation failed. 'File '/Users/xc/Dev/ezpublish/var/ezwebin_site/cache/public/ezie/14/2202-2/..1-PNG-TEST.pngh55P4u5rX2iz' could not be processed. The command '/opt/local/bin/convert -composite '' -geometry '101x65+143+90' '/Users/xc/Dev/ezpublish/var/ezwebin_site/cache/public/ezie/14/2202-2/..1-PNG-TEST.pngh55P4u5rX2iz' /Users/xc/Dev/ezpublish/extension/ezie/design/standard/images/watermarks/elephpant.png 'PNG:/Users/xc/Dev/ezpublish/var/ezwebin_site/cache/public/ezie/14/2202-2/..1-PNG-TEST.pngh55P4u5rX2iz'' resulted in an error (1): 'convert: no decode delegate for this image format `/var/tmp/magick-TlkqwUBs' @ constitute.c/ReadImage/503.'. Output: '''. in /opt/local/lib/php/ezc/ImageConversion/transformation.php on line 310

Imagick version: 6.5.6-1

This might be because of configuration in imagick, If it's, it should be documented.

Steps to reproduce

in image editor UI
1) click watermark
2) choose watermark image and position
3) click apply