Hi, when I upload new pictures, I only get the option of posting "Full Size". Large, Medium and thumbnail-size are not available.
I use 100 x 75 for Thumbnail, 300 x 225 for Medium and 800 x 600 for Large.
I've tried to upload different images with different resolutions and file formats.
(I host my own blog at my own server. WP v.2.9.2)