[JSnell]

I recently decided to delve into taking macro shots. My photography is just a hobby as likely it is for most here. I'm shooting with a Pentax K-7 using a Sigma 50mm macro and sigma em-140 DG ring flash. I've riddled both the manual for the flash and my camera and I can not get consistently developed shots with them. The lens by itself takes great shots but when I use the flash, I can take two photos with the first being visible and at the right exposure and the next being completely underdeveloped, just blackness. The flash ignites both times and I don't touch the settings (I always shoot on manual). Please help, any more information needed I'll provide. Thanks!