You could try posting the pic's actual URL, rather than the link to "bigpic" - which won't display big pictures to non-premiums.
If you're using Chrome right-click the big pic and select "Copy Image URL"
If you're using MSIE, right-click, select "Properties" then cut-and-paste the URL from the box that pops up.
If you're using Firefox, right-click and select "Copy Image Location"