how to export gradients in inkscape svg to pdf

I have an svg file with simple black lines and boxes with linear gradients (transparent to white) on top. Screenshot from inkscape.

When I export this to pdf some of the gradients disapear. Screenshot from adobe reader.

What am I doing wrong?

Files here:

http://ift.tt/1zK2ZiN http://ift.tt/1KLeSXr