You can't do that. The Dependencies feature of the Feedback module needs page breaks to be inserted between each "dependent" item, as is clearly explained in the online Help:
- First, create an item on which another item will depend on.
- Next, add a pagebreak.
- Then add the items dependent on the value of the item created before. Choose the item from the list labelled "Dependence item" and write the required value in the textbox labelled "Dependence value".