Weird American HF ballast that doesn't appear to work very well

I bought a pair of these ballasts years ago when I thought HF was the future. I liked it as it claims to drive many different types of tubes and can even drive one or two tubes.

Anyway, I'm currently installing a 5ft fixture over work bench #2, which I want to be HF as it's where I'm going to take my pictures from now on, so I fitted this in a (slightly crappy) Ring branded Tamlite batten with a trough reflector. The fixture didn't seem very bright and the tube would shimmer occasionally. I Put it on the watt meter and it was only drawing about 38 watts from the supply so obviously under driving the tube somewhat! Tried the other ballast and it did the same, I also tried various different tubes with the same results.

I've now installed the EU made Tridonic that can also be seen in this picture which works much better.