R if else for write.table if character variable has value

Say, I have data frame which I need to save with different suffix, given a value for the suffix variable or not. The suffix here is keyvalue which is of type character and I assigned a value to it.

keyvalue ="_TRP-1"
outdir= "/user/path/results"
sample= "ADAS"

And I need to write my output to the outdir using an if loop with the condition if keyvalue is not equal to na or else

This is what I tried,

if (!is.na(keyvalue)){
    write.table(output, paste(outdir, sample, keyvalue,"_scores.tsv", sep=""), sep="\t", row.names=F, quote=F)

}else{
  write.table(formatted_res_table_non_new, paste(outdir, sample_id,"_scores.tsv", sep=""), sep="\t", row.names=F, quote=F)

}

In the end, I want to have a data table/ file named, ADAS_TRP-1_scores.tsv given a keyvalue otherwise a file named, ADAS_scores.tsv. However, the above lines are not generating any tables as well as error messages, any suggestions are appreciated. Thanks