Printers won't work, driving me nuts...

Hi,

I just bought new (black) ink cartridges for my two printers (HP Desktjet 930C and Canon i250) and both won't work. The printers recognize the cartridges properly, but everytime I'm trying to print something they are producing some black lines at best. Most of the time the paper is just plain white when it comes out of the printer.

I let the printers clean the cartridges several times with absolutely no effect. What the heck is wrong with them? I didn't use the printers for some months, but since the HP cartridges have a built-in printer head at least the HP one cannot be clogged with old ink.

I'm out of ideas here. How hard can it be to get a printer running. I hate inkjet printers...

Any help appreciated!

P.S. I tried nearly anything! They just won't print...

Thanks in advance