Tie does not work

You don't say how you tried adding the tie, but my guess is you did it incorrectly. There are two correct ways:

1) while still in note input mode enter the whole note, then select quarter note duration, then press tie button to both create the quarter note and tie to it
2) enter both the whole note and quarter note, then select the whole note only and press the tie button.

I'm better you either selected a duration other than quarter note using method 1), or else you selected both notes while using method 2). Or maybe you actually entered another whole note, which would also be incorrect.

Here is step by step

click where you want to start
press N to start note input mode
press 7 (to indicate a whole note)
press a (or any other note name)
press 5 (to indicate a quarter note *it doesn't look like you did this in your example)
press + to add a quarter note

All is as you are trying to make it with no extra tied notes.

Then please attach a score that doesn't already have the tie, and give us precise step by step instructions to reproduce the problem.