Hi

May be..

=IF(ISERROR(1/INDIRECT(ADDRESS($A313,COLUMN(INDIRECT(""&$E$4&"! "&G$4&"$3:"&G$4&"$509")),1,TRUE,"DMI"))),NA(),INDI RECT(ADDRESS($A313,COLUMN(INDIRECT(""&$E$4&"! "&G$4&"$3:"&G$4&"$509")),1,TRUE,"DMI")))

or you could even custom format the cells

[=0]"#N/A";mm-dd-yyyy