Domain is www.domain.com... domain is replaced but its kept secret for privacy It ranks on the 2nd page for a popular keyword for Australia But the same Keyword in USA search engines it isn't even on the first 10 pages. Domain / Hosting is all @ an Australia Host but its .com not .com.au
Where your host is located plays a role in SERPS. If you site is hosted in Australia, it assumes that is your target market. You can research geo-targeting.
you need to geo target your SEO to get ranked on specific country. it could be the fact that your kw is more competitive in US than AU and since you are having AU hosting, its ranking well in AU. if you are targeting US, then you can change the target geography to US (is not done already) within google webmaster tool. the rest is just link building