Cannot evaluate function "last()"

[dimovnike]

I am getting item "hostname:zapache[BytesPerReqRealtime]" became not supported: Cannot evaluate function "last()".

any idea how to fix?
Thanks.

[lorf]

It's a calculated item and depend on data of other items to be available. It should become supported once the other items it depends on get some data and Zabbix decides to reevaluate it.