I am having 2 forms , 1 form is customer form that contains 1) first name , 2) last name 3) Autonumber ( unique value )

Data is already imported to this form.

The tricky part now, the product form contains  lookup field from  customer form that contains 1) last name , 2) first name 3) Auto  number ( unique value ).

No matter what i tried, i can't import anything  in the  products form when i am using more that 1 fields on the lookup field.

When i am using ONLY last name its working. 

When i am using last + first name its NOT working.

As well when i tried to use last name + first name + auto number its NOT working.

I search around all forum and i tried to workaround with spaces , to check special views for lookup fields , to try to import auto number field only and then switch the report view but nothing works.

The result that i want in products form is to have 

Last Name - First Name - Auto number(or any unique value) - Product number - ... - and more fields from product form.

I would be really happy if someone could help me with this.

Dimitris