I'm testing PictureVal property and found a strange behavior...

I have an image with height = 8 and width = 1 and an image control with height = 8, width = 91 and stretch = 2.
If I place this image in the control using Picture property, the image is showed correctly, but if I use FileToStr or LoadPicture functions to get the image and set PictureVal property with value returned from one of these functions, the left side is displayed correctly, but it goes gradually more transparent close to the right side!

I've tried this with SP2 and with a lot of image formats: PNG, BMP, GIF and JPEG and the same problem occurs.

I've tried the same in VB.Net 2005 ( argh ) and the same problem occurs.

Someone could help me to solve this (I can send a sample form to test)?