AX2012 Enterprise Portal multi-select lookup

Hi, this question is about Enterprise Portal lookup.

I'm trying to create multi-select lookup based on LogisticsLocationRole and LogisticsLocationRoleTranslation. At the moment I'm stuck on restoring the selections when the lookup is being opened.

I've tried to create view and dataset that contains both tables, but then I'm always getting error about missing uniqueIndex.

My code is almost exactly the same as in this pdf pages 70-72:

http://www.microsoft.com/en-us/download/details.aspx?id=30171

Is it possible to create multi-select lookup that is based on two or more tables?

Thanks!