Error in is.data.frame(x) : object file name' not found : pls, i dont know why always fail when i save my work

#menentukan tempat penyimpanan
setwd("C:/Users/Child-PC/Documents/Doc/Kerja/Jakarta Smart City/Data/CRM/CRM (Files) Mei 2019/R Function")

#menyimpan data ke csv
write.csv(nilai_data, file="nilai_data.csv")