Skip Custom Page after clicking Yes (MB_YESNO)

Skip Custom Page after clicking Yes (MB_YESNO)
Hi,

I have 2 custom pages in both are FileRequest-Fields.
Now it's so, when the field is empty, there comes a messagebox, in my way
(MessageBox MB_YESNO $(SkipCustomPage) IDYES skip
Abort
skip:
)
What shall i write after skip when the field is empty and should be empty, so that the original file is there and the next custom page will appear.
example code:
(leave function of the first custom page)
fuction test
.....
MessageBox MB_YESNO...
function end
(creator function of the second custom page)
fuction test2
....
function end

And what shall i write on skip at the second leave-function (for second custom page),'cause after second custom page by clicking yes shall appear the MUI_PAGE_FINISH

Thanks for help