a customer is using a Nintex Forms 2016 list form to get some data from users. They use two text fields to catch two date values. They don't use calendar controls because the expected dates are long in the past and thus entering the dates with the date picker control is not very comfortable. Instead they use input masks to help the user.
After both dates are entered they want to compare both dates where Date A must not be after Date B. However as they are both text fields the comparison is not done numerical but by string comparison.
I tried to use runtime functions formatDate and convertToDate to try parsing both text values as date and compare them afterwards but with no success.
Anyone has any ideas what other things I could try? Converting it in a workflow and getting back to the user is not really an option as the form is relatively complex which is why we'd like to do the validation directly in the form.
Thanks for any help.