Dear All

I have the following formula in cell B4:

=IF(INDIRECT("'"&$A4&"'!B$16")="N/A","N/A",INDIRECT("'"&$A4&"'!B$16"))

It refers to cell B16 in a worksheet where the name of that worksheet
is in cell A4. If N/A is found in cell B16 of that worksheet then N/A
appears in the cell where the formula is written, if not the contents
of B16 of that worksheet appear instead.

I want to drag this formula across to the right of my worksheet (to
cells C4, D4 etc) and I need the B16 to change to C16, D16 etc
accordingly. How do I modify formula so that B16 changes accordingly,
please?