Multiselect Lookup to single/multi line text. Problem with BIGINTLIST

Multiselect Lookup to single/multi line text. Problem with BIGINTLIST

Hi,

I am trying to put data from my Multiselect Lookup field into Single or Multi line text field for further use in other Forms. The Multiselect Lookup field is called Positions_names (One person can hold several positions in the organization) and the text field is Positions. So far I have a solution which only does half of the job. 

Pos = List();
for each r in input.Positions_names
{
    Pos.add(r);
}
input.Positions = Pos.toString();

The output is ID number 3232752000000042103 instead of text.

Now to get around the problem I was trying to use the reference ID function, but had no success. Please help. 

Thanks in advance!