Lookup never returns blank

[Steve6]

Hello,

Could I ask for help? I'm trying to patch a record in a Sharepoint list only if certain fields are empty and one date field contains with today's date. Currently, the function always patches the list even though no records in the list match the if() criteria.

The code my button contains: 

If(Not(IsBlank(LookUp(Employees_dump; PracovníkJméno = User().FullName && Title = ThisItem.Title && IsBlank(LongitudEnd) && IsToday(Začátek)))); CODE FOR PATCHING)

[Steve6]

Sorry, part of the first screenshot got cut off.

[iAm_ManCat · Accepted solution]

IsBlank should be checked against one of the fields within the record - try this and let me know if that works for you:

If(
   Not(
          IsBlank(
                       LookUp(Employees_dump;
                                     PracovníkJméno = User().FullName
                                        &&
                                     Title = ThisItem.Title
                                        &&
                                     IsBlank(LongitudEnd)
                                        &&
                                     IsToday(Začátek)
                      ).Title
          )
   );
   CODE FOR PATCHING
)