Adding Delimiter between Reapting Table Fields (aka Double Eval)

I have been working on a problem where Im attempting to capture a merged field from a Repeating Table (infopath form) and add a delimiter between each entry.  This is a Webform.

The purpose of adding the delimiter is so that later on from sharepoint I can export to Excel for reporting purposes.

Anyway the function I know Im supposed to use is the Eval function (actually it is supposed to be a double Eval function). 

The structure looks like this

eval(eval(group5, 'concat(../../my:MainTable/my:group5/my:Unit, ";")'), "..")

This actually does work, but the problem its not cycling through the data, its just taking the first field and each time you add a new row it just adds the first entry again.

for example

If the first field is dog

the second field is cat

and the third field is bird

it comes out dog;dog;dog;

It basically ignores the second and thrid entry as if its ignoring the double eval.

Can anyone see what Im doing wrong with this double eval?

Help URL Video: https://www.youtube.com/watch?v=ij2KqMH8FCU