Clear List button does'n work correctly

[Costenco]

Stepts to reproduce
1, Open “ListBoxr” program
2, From drop down 'Range' choose "all"
3. In radio button "Descending" from section 'Sort Order' put tick
4. In ceck box "Alphabetic" and "Numeric" from section 'Symbols' put tick on both of it
5. In field intput -> nothing

6. Click on [Add to List] button
7. Click on [Clear List] button

Expected result: Shoul be posible to click on [Clear List] button
Actual result: Is not available to click on [Clear List] button
**Priority:**Highest
**Severity:**Highest