Infopath repeating section drop down duplicate value check

Question

I have drop down list on repeating section which is populated with "Languages" list from XML file. I would like to restrict duplicate language selection in the drop down but it's not working.

Here is the interface,

Repeating section is bind with "Questions" section and drop down field is bind with "Label1"

Here is data source of drop down list,

I tried adding following formula on "result" field to get the count of duplicate selection but it is returning 0 all the time,

count(Label1[text() = preceding-sibling::*/../Questions/Question/Label1/text()]) + count(Label1[text() = following-sibling::*/../Questions/Question/Label1/text()])

Any help will be must appreciated.

Answer 1

Try and see the following step its works properly for Enter choices manually choice in drop down box Steps

1.) Add a validation rule.

2.) In condition puts following

  "Dropdown name"  is equal to  "preceding::Dropdown name" or
  "Dropdown name"  is equal to  "following::Dropdown name"

3.) Give the screen tips.

Note: please type

preceding::Dropdown name and following::Dropdown name in Use a formula area