Perhaps the EEWeb Picture uploader is sensitive to image file type (I don't see any guidelines anywhere). One would think that GIF, JPEG & PNG would all work being that this complies with HTML standards. But, perhaps not. Try changing the image format (e.g. if PNG, try converting it to JPG).
Or, maybe it's the file size. Maybe you need to compress it. Try using GIF or 8-bit PNG. Those formats do a good job of compressing the kind of image that a circuit diagram usually is (unless you scanned a hand drawn schematic).
I've had success uploading PDFs. Try putting it in a PDF. If you don't have PDF software for that (look for an Export menuitem and see if it supports PDF, or in SaveAs, look for the .pdf extension, etc.), and you're using a MS Windows machine, down load Bullzip and install it. Bullzip acts like a printer. In your application, select the Print menu item and then find Bullzip in the list of printers. It will "print" a PDF.
