The AND
formula, when used as part of an array formula, does not evaluate the whole array.
{=AND(A1:D1="")}
would return TRUE if a value is entered in the range B1:D1 and FALSE only if value is entered in A1
=IF(AND(A1="",B1="",C1="",D1=""),TRUE,FALSE)
would return FALSE if value is entered in any cell in range A1:D1
Ctrl
+Shift
+Enter
to enter as an array formulaArray formula should be evaluated correctly and return FALSE when a value is entered in any cell in range A1:D1.