Creating/Converting .arff files

Hello everyone,

I'm new to weka and I'm trying to convert some .txt files to .arff format.
For example the brown corpus: http://www.sls.hawaii.edu/bley-vroman/brown_corpus.html

I've tried using this tool for the task: http://weka.wikispaces.com/Text+cate...tion+with+WEKA

But when I try to use the provided command "java weka.core.converters.TextDirectoryLoader -dir text_example > text_example.arff" I get
the following error: Main class weka.core.converters.TextDirectoryLoader can't be found or loaded.

(I'm using Windows 7 x64 and Weka 3.9.0 developer version, opened the command prompt, navigated to the folder which contains my subfolder with the .txt file and entered this command)



I also tried the same with the weka explorer: Open File -> Chose the folder with the subfolder (with .txt) -> After error message I chose TextDirectoryLoader -> Click ok with provided parameters

Unfortunately I only get a .arff file with 1kb this way...

Is there a better way to convert a .txt file to a .arff file? Am I doing something wrong with the TextDirectoryLoader?

I hope someone can help me because it would take me weeks to create the .arff files on my own :(
Thanks in advance!