Statistical Analysis (one-factor/paired) not working

Hello,
I wanted to use the tool -Statistical Analysis (one-factor) - with paired data. I have prepared my dataset according to your example on the data format page (e.g. Label of sample 1 - T1 is 1 and Label of sample 1 - T2 is -1, and so on). However, as soon as I upload my data file and click on “Edit groups”, new labels are assigned to my samples and the sample pairs no longer match (e.g. Label of sample 1 - T1 is now 14 and Label of sample 1 - T2 is 5, and so on). Do you know what the problem could be?

Thank you in advance!