Links showing N/A
 

I have a worksheet with 8 cells that link to 8 cells on a different
worksheet. 5 of these always pick up the value of the linked cell. The other
three show "N/A". When i open the source file, the problem cells update with
the values OK. But then when closed the N/A appears back.

I have tried to identify what is different with the three "rogue" cells on
the source sheets. Could it have something to do with them being merged or
locked, protected? I feel it is something to do with one of these but there
are other cells (e.g. merged) that are updating OK.

Any suggestions gratefully received! - thanks in advance.