Dear Kutu, I'll say in points...
1. provide the link of that thread you had opened & was closed without no support. we'll take a look & will take care off...
2. I can say, you have a low idea about vBulletin. vBulletin may not check external images by default but if we make any tweak ?
3. As you can see, your getting the msg saying
You may not link to external websites in your signature. Is becuz we tweaked the vBulletin

& we did this bcuz to protect this forum from posting or signature spaming. PM me you uploaded signature image link, i'll add it as your signature.
Added:
4. try now, you can use any links for your signature..
thanks..