Can not create one-to-one relationship

Hello everyone:

Please help me solve this mystery. 

I have a big survey database which contains around 1000 or more variables. In order to make life easier I picked up only the key variables and put them in different tables based on the brands.

For example in my "filter table" I have "respondent ID", "customer segments" and "country of origin".

Then in my "Brand A" table I have "respondent ID", "Are you interested in buying Brand A", "Did you actually purchase Brand A" etc. 

Finally in my "Brand B" table I have "respondent ID", "Are you interested in buying Brand B", "Did you actually purchase Brand B" etc.

All the tables have same amount of rows, and I have replaced any missing cells with a "missing/NA" label.

Each of the respondent ID is unique and associated with one and only one record in another table, which definetly sounded like a one-to-one relationship to me. However when linking the brand tables to the filter table, Brand A table formed an one-to-one relationship while Brand B table can only fromed an one-to-many relationship.

Please help me with this, thank you very much!