Still error on Image Filter

Tuesday 17 March 2009 9:01:10 am

[ImageMagick]
IsEnabled=true
ExecutablePath=/usr/bin
Executable=convert

Filters[]=thumb=-resize 'x%1' -resize '%1x<' -resize 50%
Filters[]=centerimg=-gravity center -crop %1x%2+0+0 +repage
Filters[]=strip=-strip

[AliasSettings]
AliasList[]
AliasList[]=reference
AliasList[]=thumbnail_gallery

[reference]
Reference=
Filters[]
Filters[]=geometry/scaledownonly=600;600

[thumbnail_gallery]
Reference=
Filters[]
Filters[]=thumb=200
Filters[]=centerimg=100;100
Filters[]=strip=

Problem happens when image in GIF format. It is not resize the image after crop (in height dimension exactly). JPG is very good.

Is there any bug? Or the command is not good?