Started playing with OSL yesteday. It fails feeding output (color) to receiving node!

Replacing script node with anything builtin, including Combine RGB, and Geometry (Position) feeds the Color input of the diffuse “shader” as expected. But connecting the script back again results in “silence” once again. Just like yesterday, it worked initially, but some random/unknown “event” occurred, and it stopped working. Just like yesterday, whatever went wrong, that wrong was saved (with or without quotes) inside the blend (when I saved), so restarting blender and loading the blend file gives same symptoms.

Win7 32bit Home Premium.
Blender 2.78a (yesterday: 2.78)

EDIT:

shader test_color(
    output color Color = color(0.0, 1.0, 0.0))
{
    Color = color(1.0, 0.0, 0.0);
}

EDIT 2:

Errr… I don’t know why, but OSL was un-ticked (how did that happen ???).

I forgot to provide update. As it turned out, the reason for OSL being disabled was, not once, but twice (different days), that again I had pushed the mouse out of my way (the text editor) so the cursor landed in the properties editor, over the “Open Shading Language” checkbox. Guess what happened when I pressed enter…