Check if there is any JavaScript error on the page (F12 → Console). To debug your codes, press F12 → Source, add a break point to step through the codes.
“Prz+Unt” is wrong field variable name (which is always alphanumerical, not work in older versions either). If it is really “Prz+Unt” in your database, the field variable name will be “Prz2BUnt”, see the topic Tools → Database, Table and Field Variable Names in the help file.
Your code should also check the result of $row[“xxx”].toNumber() which may be null if the field is not filled. In such case your code will fail and you should see error in F12 → Console (assume you use Chrome).