使用RColorBrewer时失败？当我使用RColorBrewer时，颜色不会改变

Question

当我使用RColorBrewer时，颜色不变。我想知道为什么吗？

library(ggplot2)
library(reshape2)
library(RColorBrewer)

data1 <- seq(1, 300, 3)
data2 <- seq(1, 100, 0.5)
acf1 <- acf(data1, plot = F, lag.max = 25)
acf2 <- acf(data2, plot = F, lag.max = 25)
df<- data.frame(lag = acf1$lag,acf1=acf1$acf,acf2=acf2$acf)
colnames(df)<-c("lag","data1","data2")
data<-melt(df,id="lag")
ggplot(data=data[data$variable=="data2",], aes(x = lag, y = value, 
                                           fill = variable)) + 
geom_area(position = "dodge") +
geom_area(data=data[data$variable=="data1",],
        aes(x = lag, y = value, fill=variable), position = "dodge")+
 scale_colour_brewer("Colors in Spectral", palette="Spectral")