in the dynatabframe code the ->pack() is already there so it's better not to call it again.

Looking at the demo (e.g. inside zip on this page) it seems that when packing the dynatabframe itself the -fill => 'both' option may be necessary.

With your grid approach you can get the same effect by adding -sticky => 'nsew' as a grid option.

Either of these solved the problem for me.