Next image fails

I'm using ubuntu 14.04, apache 2.4. I can load one image using url query string parameter 'image' and 'folder', however when i click on the next button, white page appear. It happens with the new images or with the images in the example_folder.

Secondly, i would like to ask how one generate Mask from annotations available in the form of xml. The labelme loads them but when i press process/done, it says i need to scribble first. Is it possible to convert xml annotations to colored masks (i.e. colored label images)?

Thanks