I'd suggest using spaces instead of tabs. If you use tabs, you have to take into account the spacing that the tab is using, and that can vary.

To use spaces instead do this:

* Get the longest label and add 1
SELECT max(len(label_name))+1 ;
   FROM mydb!table1 ;
   INTO ARRAY laMaxCaption

Then, when you format the return string, change the line to this:

m.lcReturn = m.lcReturn + ;
      ALLTRIM(m.laCaptions(i,1)) + ;
      REPLICATE(' ',laMaxCaption[1]-len(laCaptions[i,1])+[: ]+ ;
      TRANSFORM(EVALUATE(m.laCaptions(i,2)))+CHR