R-Programming Sentiment Analysis

Siang, maaf mau nanya nih, ada yang tau gak kodingan di rstudio kalo ada yang error kek gini solusinya gimana ya? makasih..

input: #Creating three different data frames for Score, Positive and Negative #Removing text column from data frame test1$text=NULL

output: Error: invalid assignment for reference class field ‘text’, should be from class “character” or a subclass (was class “NULL”)