What size in pixel dimensions and kilobytes is the signature pic?
Does the pic show up when you "preview" your signature changes as you are making them?
Is the pic uploaded to EO or is it stored on another Web site?
What steps, exactly, are you taking to insert the pic into your sig?
What's the URL of the image?
Go to your settings, delete the pic from the signature, and start over.
When you start over, write down or remember exactly the steps you take to put it back.