Getting class probabilities w/ SMO

First of all, sorry for the naive question i'm new to weka and
to classification so...

I have trained text data using SMO to classify as positive and negative
when I test an instance, I would like to get the probability of the prediction,
I was reading that I could do this using -M however when I use this
option for training, when I do the test I still get the output below,
which doesn't give a probability of the class prediction, just the prediction
itself.  What am I doing wrong here???

btw this is the command I am using to build the model...
java -Xmx2048m -classpath /Users/lisa/Desktop/weka-3-5-8/weka.jar weka.classifiers.functions.SMO -d /tmp/movie_model.model -c first -t movie_training.arff -M

...
 +       0.0019 * (normalized) young
 +      -0.0679 * (normalized) your
 -       0.7147

Number of kernel evaluations: 372592 (97.499% cached)



Time taken to build model: 6.07 seconds

=== Predictions on test set ===

 inst#,    actual, predicted, error, probability distribution
     1      1:neg      1:neg         *1      0    

=== Evaluation on test set ===
=== Summary ===

Correctly Classified Instances           1              100      %
Incorrectly Classified Instances         0                0      %
Kappa statistic                          1    
Mean absolute error                      0    
Root mean squared error                  0    
Relative absolute error                  0      %
Root relative squared error              0      %
Total Number of Instances                1    

=== Detailed Accuracy By Class ===

TP Rate   FP Rate   Precision   Recall  F-Measure   Class
  1         0          1         1         1        neg
  0         0          0         0         0        pos

=== Confusion Matrix ===

 a b   <-- classified as
 1 0 | a = neg
 0 0 | b = pos