The syntax should be:

iif(condition1, return1,return2)

But you have:
iif(condition1, return1,return2,0)



>Am i doing something wrong with this:
>
>

IIF(EMPTY(Llamadas.fcita),(IIF(EMPTY(Llamadas.fatencion),(DATETIME()-Llamadas.fllamada)/3600,0)),(DATETIME()-Llamadas.fcita)/3600,0)

>
>Thanks for the help