Golang，写入csv文件结果文件有时为空

I'm working on a parsetable and decided I'd like to see the table in a readable format. When I created the csv with a large grammar, it successfully outputs the results. However, the parse table isn't correct. So, I'm trying to test with a more simple grammar. For some reason this code produces a csv file with my large grammar, but with the simple grammar the file is blank. What am I doing wrong here?

func WriteTableToFile() {
    f, err := os.Create("tableFile3.csv")
    Check(err)
    defer f.Close()
    w := csv.NewWriter(f)
    var tsl []string
    tsl = append(tsl, " ")
    tsl, _ = UnionSlices(tsl, TerminalSymbolList)
    w.Write(tsl)
    fmt.Println(tsl)

    for ntk := range ParseTable {
        var writeSlice []string
        writeSlice = append(writeSlice, ntk)
        for _, tk := range TerminalSymbolList {
            for _, p := range ParseTable[ntk][tk] {
                writeSlice = append(writeSlice, p)
                fmt.Println("appending ", p)
            }
        }
        w.Write(writeSlice)
        fmt.Println("wrote ", writeSlice)
    }
}