problem with deleting buttons in a loop

[Björnke von Gierke]

i am deleting buttons in a loop, but somehow there is always a button 
that does not get deleted,  and I cant find out why. There is one other 
button in the group.
Can anyone explain this behaviour? Is this a bug, or am I making a 
stupid mistake?

   put the number of buttons in group "points" into a
   repeat with x = a down to 1
     if word one of the short name of button x = "point" then
       delete button x
     end if
   end repeat

Thank you in advance
Bjoernke