fill flash

What do other people do to get fill flash? I am doing something wrong.

I have a K10D and an AF540 flash.

I have tried PTTL mode and I get no ambiant light.

I have also tried using Av mode and the flash on A mode. If I set the iso at 400, the flash wants an f-stop of 5.6, which does not do much for the ambiant light.

Ideally I would like a slow shitter speed and a brief flash pop to get faces.

Here are two shots taken last night, one with flash and one without.

I like the lighting one without flash except for the blurry aspect. The K10s SR probably helped a little, but not enough.

Thanks, Shane