How to fix an a concatenate formula conditional to a non blank cell

I'm trying to concatenate cells from columns C, D & E as long as Cell A is not blank (has a value)

Cell A is a formula based on listing weekdays:

=IF(WORKDAY(A$28-1;ROW(21:21))>A$29;"";WORKDAY(A$28-1;ROW(21:21)))

My concatenate formula is as follows:

=IF(ISBLANK(A24);"";CONCATENATE(E24;CHAR(10);D24;CHAR(10);C24))

The formula is still concatenating even if Cell A is blank

snapshot of excel