How to refresh next dialog

OK:

I've been fighting with this for the last several hours and here's the flow:

1) User selects from radio buttons and the response is stored in variables on next (if option 1 set variable 1 = name 1, set variable 2 = path 1... (continue this for each of 3 options))
2) a custom dialog is displayed where text uses the variables from the previous radio button dialogs
3) if the user clicks back on the custom dialog the radio buttons dialog comes back, a new option is selected and next is clicked; however the text isn't updated

I've fiddled around with various checks of %_SB_BUTTONID%, %_SB_DIALOGID%, and %_SB_DIALOGNEXID% and various "update next dialog" statements in various parts of my script, but for the life of me I cannot get it to work.