title: SummaryWriter not writing summaries to file
body: <p>I'm trying to use tensorflow's SummaryWriter, however it does not seem to write events, images, or histograms to file. However it does write the graph to file, (which I can then see in tensorboard), indicating at least, tensorboard and SummaryWriter know where my logdir is. </p>
  
  <p>Here is my (simplified) code, broken up by omitted code blocks:</p>
  
  <pre><code>sess = tf.Session()
  W_conv1 = tf.Variable(tf.truncated_normal([5,5,3, hidden1_size], stddev = 0.01), name = 'W_conv1')
  b_conv1 = tf.Variable(tf.constant(0.01, shape=[hidden1_size]), name = 'b_conv1')
  
  #to visualize the weights of the first layer...
  sum2 = tf.image_summary('first layer weights', tf.transpose(W_conv1, perm = [3, 0, 1, 2]), max_images = 16)
  
  h_conv1 = tf.nn.relu(b_conv1 + conv(x, W_conv1))
  
  #to visualize how many dead relu's we have
  sum1 = tf.scalar_summary('conv1', tf.nn.zero_fraction(h_conv1))
  </code></pre>
  
  <p>.... More layers</p>
  
  <pre><code>softmax = {}
  cross_entropy = tf.Variable(0.0)
  softmax[0] = tf.nn.softmax(fc_out)
  cross_entropy += -tf.reduce_sum(y_*tf.log(softmax[0]))
  </code></pre>
  
  <p>.... Reccurrent Part</p>
  
  <pre><code>sum3 = tf.histogram_summary('cross entropy', cross_entropy)
  
  
  lr = tf.Variable(tf.constant(1e-3))
  lr_change = tf.assign(lr, tf.mul(.1, lr))
  
  train_step = tf.train.AdamOptimizer(lr).minimize(cross_entropy)
  
  merged=tf.merge_all_summaries()
  writer = tf.train.SummaryWriter("./logs", sess.graph_def, flush_secs = 5)
  
  sess.run(tf.initialize_all_variables())
  </code></pre>
  
  <p>.... and then the training code:</p>
  
  <pre><code>for i in range(train_iter):
      batch_i = np.random.randint(0, len(X_t), [batch_size])
      X_batch = X_t[batch_i]
      y_batch = y_t[batch_i]
  
      summary_str, _, loss = sess.run([merged, train_step, cross_entropy], feed_dict = {x: X_batch, y_: y_batch}) 
  
      writer.add_summary(summary_str, i)
      writer.flush()
      saver.save(sess, 'RNN_model.ckpt', global_step = i)
  </code></pre>
  
  <p>Then when I load tensorboard, and look at the events tab, I see the following error:</p>
  
  <blockquote>
    <p>No scalar summary tags were found.</p>
    
    <p>Maybe data hasn't loaded yet, or maybe you need to add some >tf.scalar_summary ops to your graph, and serialize them using the >tf.training.summary_io.SummaryWriter.</p>
  </blockquote>
  
  <p>I added the writer.flush() statement, because after searching on both stack exchange on github, that's a common suggestion. Issue not fixed. </p>
  
  <p>In my logs file, only the graph_def is written, no other files are written during training. </p>
  
  <p>I'm using tensorflow '0.7.1' on mac 0SX el-capitan. </p>
  
  <p>Thanks!</p>