One cannot reference another sheet in a formula by using the UI.
1. Open your spreadsheet demonstration app.
2. Create two work pages.
3. Enter some information on the first page.
4 .go to the second page, select any cell, and press =
5. navigate to the first page and select a cell with data in it.
6. Check the second page again, there is no reference link.
Workaround: manually type the sheet name in the formula