[R] Error in defining function

[Megh Dal]

Can anyone please tell me why I am getting this error?

library(zoo)
Z.index <- as.Date(sample(12450:15500, 3000))
Z.data <- matrix(rnorm(300), ncol = 1)

data1 <- zoo(Z.data, Z.index)

fnc = function(data1)
    {
    selection2 = select.list(c("Mean"), multiple = F)

     Mean = function(dataa) mean(dataa)

     return(aggregate(data1, as.yearqtr, selection2))
    }
    
    fnc(data1)

I got following error :
Error in get(as.character(FUN), mode = "function", envir = envir) : 
  variable "Mean" of mode "function" was not found

What would be the correct way?

Regards,