Penatax 280T flash issue

I bought a 280T flash online to use with my Super A in TTL mode and received it this morning. It fires up, the orange ready light works, and will flash when the test button is pushed and also the flash icon (lightning bolt) is indicated in the viewfinder of the Super A, however it will not fire in either TTL or the red or green modes when attached to the camera. All other flashes work on my Super A so it doesn't seem to be a problem with the camera itself, and I have tested the flash in the non TTL modes on a Pentax ME but the same thing happens. I put in new batteries and the contacts seem clean, am at a loss. Any experience/ advice in this situation or does it seem like I got a dud? The seller maintains that it works perfectly on his LX.

I have used a 280T on all of those bodies and it has worked fine. I would guess you have a bad unit.

Thanks for the reply, yes after about half a roll it started working perfectly, it's fine now. I thought it had been in regular use by the previous wonder but I guess it hadn't been fired in a while. Anyway very glad it's working now.