I have setup a Force.com Site with access to Visualforce page, however receive an error message when trying to use the Lookup fields on the page.

Some troubleshooting I've done so far:

1. Grant access to relevant VF pages
2. Grant access to relevant Objects/fields/record types of the Lookup relationship
3. Grant access to Site Standard Pages "Lookup Page"
4. Added my IP Addresses to "Network Access" IP ranges

Error:

What am I missing here?

I have setup a Force.com Site with access to Visualforce page, however receive an error message when trying to use the Lookup fields on the page.

Some troubleshooting I've done so far:

1. Grant access to relevant VF pages
2. Grant access to relevant Objects/fields/record types of the Lookup relationship
3. Grant access to Site Standard Pages "Lookup Page"
4. Added my IP Addresses to "Network Access" IP ranges

Error:

What am I missing here?