Control Panel » Forum Permissions
Select you gallery forum
Maximum size of gallery images
Set this in bytes per group
Also there is a note below the field on this setting.
That will show the max file size set by php.ini.
"If this forum is a gallery forum, this setting dictates how large each image may be. Max size set in php.ini is 2M, so you may not exceed this size."
For my site it is 2MB. Double check yours to see if it is set to 0.
