Error in get(as.character(FUN), mode = "function", envir = envir) : object 'f' of mode 'function' was not found

First I read the CSV file.
Dat<-read.csv("femaleMiceWeights.csv",header = TRUE,sep =",",dec=".")
Diet Bodyweight
1 chow 21.51
2 chow 28.14
3 chow 24.04
4 chow 23.45
5 chow 23.68
6 chow 19.79
7 chow 28.40
8 chow 20.98
9 chow 22.51
10 chow 20.10
11 chow 26.91
12 chow 26.25
13 hf 25.71
14 hf 26.37
15 hf 22.80
16 hf 25.34
17 hf 24.97
18 hf 28.14
19 hf 29.58
20 hf 30.92
21 hf 34.02
22 hf 21.90
23 hf 31.53
24 hf 20.73

afterwards i typed this command
controls<-Filter(Dat,Diet=="chow")
it shows this error
Error in get(as.character(FUN), mode = "function", envir = envir) :
object 'f' of mode 'function' was not found
Please anybody solve this issue, i am not able to uderstand this issue