I have a look up field on a form. I've tried to get the value of that lookup field into a formula field but it returns the entry ID such as:

1365899000000729278

I have previously used a code in deluge script to get the value by using this technique:

Checkpoint[ID == input.Checkpoint].Checkpoint

However, if I try to use this in a formula field i get an error stating:

"Expression not supported in formula"

Is there anyway I can get the value of a lookup field into a formula field? I need to take the value of a look up field and the value of another text field and join them together in a formula field.

Many thanks!

Greg