using trainDocTopicModel to approximate p(topic|document)

[mw]

Hello,

i am trying to use a topicmodel to approximate p(topic|document) like this
TopicModel model = new TopicModel(hadoopConf, conf.getEta(), 
conf.getAlpha(), dict trainingThreads, modelWeight,
                    models);
Vector docTopics = new DenseVector(new 
double[model.getNumTopics()]).assign(1.0/model.getNumTopics());
Matrix docTopicModel = new SparseRowMatrix(model.getNumTopics(), 
document.size());
int maxIters = 5000;
for(int i = 0; i < maxIters; i++) {
     model.trainDocTopicModel(document, docTopics, docTopicModel);
}

For some reason the values in docTopics dont change much.
Does that indicate that the current document does not fit into the model?
Could there be another explanation?

Best,
Max