#VALUE! ERROR

Hi,

I have some cells that have #value! error as there are elements missing from some of the cells included in the formula. I would like to replace the ones that get this with text 'NOT AVAILABLE' but if there is no error then it continues to produce formula result as normal.

I have tried this formula below but I can't seem to get it to work.

=IF(AA10="#VALUE!","NOT AVAILABLE",(G10+AA10)/0.85)

Appreciate if someone could help me

Many thanks