Getting value label in multi selected items

Hi all,
I'm having a problem getting selected labels from select_multiple questions to be used in the proceeding questions.

it's working fine if the first item alone or the first item with other items is selected, but if the second item alone is selected, I can't seem to get the selected label. it's showing empty.

This is a function I'm using to get labels, there are about 7 answer options in the question with mainproblem variable.
jr:choice-name(selected-at(${mainproblem}, 0), '${mainproblem}')
jr:choice-name(selected-at(${mainproblem}, 1), '${mainproblem}')

I have checked [this thread]( but it's different from my problem.

I have attached the excel file.
[Lomiademo.xls|attachment](upload://dYa8DtxGkVHUSYvGAuYuLct6WbB.xls) (80 KB)

Please I need your assistance on this. 

Hi @sandet
Welcome to the ODK forum. We're glad you're here. When you get a chance, please introduce yourself on this forum thread.

Could you attach your form? It would be easier to help you then.