Multiple group name with for each @section using rtf template

I have an rtf template and the user's requirement is to print a batch of documents based on the transaction number.

Now to do this, I search something in Google and I found a function <?for-each@section:group_name?>.

I tried the above function and it works in my header and footer portion, however, my problem is the data from the other group_name(G_2) is not showing and return as blank.

Below is the syntax I'm using.

<?for-each:G_2?>

<?for-each@section:G_1?>

<?element_name?> (Note: this element is from G_2?>

<?end for-each?>

<?end for-each?>

Regards,

Lawrence