put the openStacks

[Richmond]

So . . .

If I type
*
put the openStacks into fld "STAX"*

in the *messageBox* (assuming that I have an open stack containing a 
listField called "STAX")

I get a lovely list of . . . wait for it . . . the open stacks.

However (8.1.9) if I have a button on that stack containing

*on mouseUp
put the openStacks into fld "STAX"
end mouseUp*

the thing does not work.

Any bright ideas about where I'm going wrong?

Richmond.