Unable to see preset preview image

I apologize if this is a dup; I've been digging around related threads all day. There are so many conflicting queries going on it is hard to tell exactly what problems people are having.

• A fairly clean and up-to-date Drupal install (no views, panels, or CCK)
• ImageAPI 6.x-1.6, with ImageAPI GD2 enabled
• Transliteration 6.x-2.1
• Private download method, to /uploads/mysite
• Temp directory is /tmp
• Status report shows all clear

I created a preset "thumbnail", scale to 92x92. The preview image doesn't display properly (see attachment). The sample image does exist at /uploads/mysite/imagecache_sample.png. The /uploads/mysite/imagecache/thumbnail directory has been created.

The log shows these errors:

• Parameter 1 to imageapi_gd_image_resize() expected to be a reference, value given in /Users/jason/Sites/mysite/sites/all/modules/imageapi/imageapi.module on line 165.
• imagecache_scale_image failed. image: /uploads/mysite/imagecache_sample.png, data: Array ( [width] => 92 [height] => 92 [upscale] => 0 ) .
• action(id:2): imagecache_scale failed for /uploads/mysite/imagecache_sample.png
• Failed generating an image from imagecache_sample.png using imagecache preset thumbnail.

All from the referrer: http://mysite/system/files/imagecache/thumbnail/imagecache_sample.png?12...

Any ideas?