R Script Error: comparison (6) is possible only for atomic and list types Traceback:

I am trying to create a new variable called exp_error in the same dataset that takes the value “FALSE” whenever experience is negative, and “TRUE” otherwise. In the line that does this, I keep getting an error Message.

mutate(india04_new, exp = age - 18)
mutate(india04_new, exp_error = ifelse(exp > 0, "TRUE", "FALSE"))

Error message:

Error in exp > 0: comparison (6) is possible only for atomic and list types
Traceback:

1. mutate(india04_new, exp_error = ifelse(exp > 0, "TRUE", "FALSE"))
2. mutate.tbl_df(india04_new, exp_error = ifelse(exp > 0, "TRUE", 
 .     "FALSE"))
3. mutate_impl(.data, dots, caller_env())
4. ifelse(exp > 0, "TRUE", "FALSE")