Removing rows with duplicates

I have a table where I want to remove the rows that have duplicated values (in a spesific column). When I test the remove-duplicates function on that column alone it works, but not when I mark the entire table. When I do that and cross off the column I want to base the removal on, it can't find any duplicates. I have made sure there are duplicates there by using COUNTIF and also checked that the cells have the right formate (general). Does anyone have any idea of what is wrong?

Okay! Thank you Pepe Le Mokko!