Unsuccessfully trying to change reservation

[Nick10]

An upcoming guest wants to add a day to her upcoming reservation.  Because I  have a two day minimum, she can't just do it as a separate transaction. 

When I go to 'your reservations' and click on 'change or cancel reservation', I get all the way done by clicking on 'submit changes'.  Then it returns me to the 'change  reservations' page with no changes made. 

I did this 3 times about 8 hours ago and, as of yet, neither my tenant or myself has received an email regarding this issue.

What am I doing wrong?

Thanks,

Nick