> i have set labels for all 3 (prevlabel, nextlabel & lastlabel) and still there is a "finish" button under my one question.
This thread is about *instruction* pages (i.e. <page> elements), *not* <surveypage>s. Since you mention a questions, you must be talking about the latter. The labels work like this:
/ nextlabel = "Nextlabel >>"
/ backlabel = "<< Backlabel"
/ finishlabel = "Finishlabel >>"
/ pages = [1=a; 2=b]
/ caption = "First page"
/ caption = "Second (and final) page"