Trying To Link Lookup to Another Form so that fields will be auto filled.

Trying To Link Lookup to Another Form so that fields will be auto filled.

As said in my subject title above,

I'm trying to link my Lookup field to Another field in another form so that once I key in e.g. Name, the address of the person will be filled automatically. I have tried editing the fields actions , however, I got two of the either errors saying that 

Error in statement at line number 1
The Left expression is of type STRING and the right expression is of type BIGINT And the operator == is not valid here

(When my BIGINT is actually the lookup field. Look at pic 3 )

OR

Error at line 1 : name not expected
(Look at pic 1 & 2)

Can anyone help?