[R] Problems creating a Panel

[Luis Felipe Parra]

Hello, I am trying to create a panel with the attached data frame. using the
following code:

> PanelRio =  DataRiopaila[which(duplicated(DataRiopaila$SEC_STE)==T),]
> PanelRio=plm.data(PanelRio,index=c("SEC_STE","FechaSiembra"))
series
Pluv3Meses,PluvMes4al10,Pluv2UltimosMeses,Rad3Meses,RadMes4al10,Rad2UltimosMeses
are NA and have been removed

It tells me it removes couple of series because they are NA, and I don't
understand why because if I do:

> PanelRio =  DataRiopaila[which(duplicated(DataRiopaila$SEC_STE)==T),]
> length(which(is.na(PanelRio[,"Pluv3Meses"])==T))
[1] 474
> nrow(PanelRio)
[1] 4129

which means there are still around 3500 entries which aren't NA. Does
anybody what can be going on?

Thank you

Felipe Parra