Lost instruction manual

Read your manual, then call the maker

Check your lens there is often a AF/MF auto/manual focus switch

Other than that it could be a problem with the camera take it to your dealer

You can download the manual from the manufacturer's web site at
http://www.pentaximaging.com/files/manual/istDL_web.pdf

This is a common problem...sometimes you have to turn it on a couple of times.

Is your "exposure compensation" (the button with the +/-) set to "0" or some other setting?

Did you try formatting the new card in the camera before you tried to use it?

Pentax *ist DL User Manual
Pentax *ist DL Software Manual

Send it to me, I will operate it for two years then send it back.

pentax istDL does not support TTL flash metering unlike most of the other pentax DSLRs. You need a flash that is P-TTL. How annoying hey? I was pretty bummed, but it made me learn to shoot fully manual...

i think that there is only one P-TTL flash on the market at present. (AF540 or something)

good luck...

Looks like its true... Another major disadvantage. Removing TTL means removing one more hardware piece - TTL sensor. Pentax removed almost every nice feature, which needs some aditional or more expensive hardware: no TTL flash, less AF points, pentamirror... Seems like I bought Ds right in time.