See msg#6.

As an aside, you have many formulae with SUM in, most of which are unnecessary:
=SUM(D3*$A$21)/100
can be:
=D3*$A$21/100

=SUM(D3*$A$22)/100*0.95
can be:
=D3*$A$22/100*0.95

=SUM(C3/K3)
becomes:
=C3/K3

=SUM(E3+F3)
can be either:
=E3+F3
or:
=SUM(E3,F3)
or:
=SUM(E3:F3)

=SUM((B3-B2)/L3)
goes to:
=(B3-B2)/L3