How to apply vertical and horizontal blur shaders?

I need to apply two pass box blur to a texture. My problem is they don’t act together only the last one that applied gives the result.

original_tex 1024x1024 -> [blur_horiz] -> temp_texture 128x1024

temp_texture 128x1024 -> [blur_vertic] -> result_texture 128x128

Additional tip: you can use the same shader for both blur passes by manipulating the texture coordinates of the fullscreen quad.