Repositories added but don't work

I have a weird problem, which I never faced on onother ubuntu or other linux distro.
When I add a repository with add-apt-repository, seems that all go well, but I cannot find any software from that repository.
If I open synaptics I can see the new repository on settings-> repositories-> other software tab and is checkd, but doesn' t appear at all on origin filter, and no software is available. I tried to uncheck recheck and reload several times but doesn' t work. I've this problem first with kernel ppa, and after some tries it works, but now I used a different repository, the problem is the same, but doesn' t work. I also tried from terninal, but I get same software not found error.
The software of the repository exists. I'm saying this because on kernel ppa the software was deleted(the entry on origin appears after some tries though).
Any help or solution?

Just to report that seems doesn't happen all times. I add another repository today and worked normally from first time(I've add a ppa total 3 times so far). Only this:
https://launchpad.net/~lukas-hetzenecke ... /+packages
never worked.
So maybe the problem is with the above only.
I'll test it farther and I'll post again if this problem appears again.

Did you check that the "Keys" for the PPA's are also present??.

Regards Wolfman

Yes, for the keys, and yes for link' s procedure.

Hi,

you could try changing the download location for your software sources and by picking a country first; then selecting "Select Best Server", this may well help you with your problem!!.

Regards Wolfman

Hi,

you could try changing the download location for your software sources and by picking a country first; then selecting "Select Best Server", this may well help you with your problem!!.

Regards Wolfman

I tried that to, didn' t work for the link I posted before. I tried best server, I tried every server for my country, I tried different servers for other countries too, didn' help.