Matchchunk problem?

[David Vaughan]

The following script:
   put "frog frog"  into avar
   put 1 into x
   put 1 into y
   get matchchunk(avar,"F*g",x,y)
   put it  && x && y

returns "true  "  ...so what happened to the chunk values expected in 
"x" and "y" ?
What I was REALLY trying to test was whether it would return in x and y 
"1 4" or "1 9", but now I would love to know why I get neither 
(matchtext fails similarly). What have I done wrong?

thanks
David