My google sheets javascript program does not delete rows, why?

Question

I have a problem deleting rows from my sheet. This code just won't delete rows. Could someone please explain?

function myFunction() {
      var doc = SpreadsheetApp.getActiveSpreadsheet();
      var sheet = doc.getSheetByName("Taulukko1");
      
      var values = sheet.getRange("A1:K28").getValues();
      
      var row_del = new Array();
        
      for(var i=0;i< values.length; i++)
      {
          if(values[i][7] == '17.9.2020'){
          row_del.push(i); 
      }
    }
     
      for (var i = row_del.length - 1; i>=0; i--)   {     
         sheet.deleteRow(row_del[i]);   
   }
    
}