I'm not going to try to upload or download anything. To make images work in your database from a form, you need two things.
1. A complete path to the image file.
2. The correct image-file processing code included in the Access installation.
For instance (trivial example here), if you didn't include JPEG wizards in the Office install, Office won't easily be able to display JPEC files. It does not matter that Windows itself can open and correctly display the file. You need to set up proper references to the correct file handler for Access.
In a form, if you have a table with a field that holds the image specs, then in the form's OnCurrent event you can load a path to a form's image control. Play with the settings.
If you are giving the correct path and loaded the proper wizard, this should work. Unless you did something silly like change the name of the file. Because, you see, Windows actually BELIEVES what you tell it about what type of file it is based on... the file type.
So if you put a .WMF file type on a file, it had better be a Windows MetaFile image. If you put a .JPG file type on a file, it had better be a JPEG file. Etc. etc. etc. Also, beware of files that include internal checksums or other methods of detecting corruption. If the file is corrupted, it might not show correctly. Another thought is that you didn't say what version of Access or Windows you are running. If it is WinXP with service pack 2 installed, your machine's security setting has been ramped up. Because of that, some types of image don't want to play any more.
If you were trying to link images via OLE in a table vs. opening a form, you have opened up another can of worms having to do with OLE activation. This is yet another hot-button for Windows security.