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I get this error while trying to install a package as follows:

sudo add-apt-repository ppa:v-launchpad-jochen-sprickerhof-de/pcl
sudo apt-get update
sudo apt-get install libpcl-all

The first two don't issue any error message, but the last one gives:

The following packages have unmet dependencies:  libpcl-all : Depends: libpcl-
1.3-all but it is not going to be installed E: Unable to correct problems, you have 
held broken packages.

How is that even possible? If package xxx depends on package yyy, why isn't yyy installed then? Usually, when you run apt-get install xxx it will automatically install all packages xxx depends on. What may prevent it from doing so?

but it is not going to be installed

well why isn't it?

share|improve this question

closed as too localized by Luis Alvarado, Ringtail, bodhi.zazen, fossfreedom Apr 5 '12 at 8:35

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Have you tried to apt-get install the dependency manually? Did it give you any error? – Wolfger Dec 27 '11 at 18:13
Probably because it can't be found. Check apt-cache policy yyy to find out. – psusi Dec 27 '11 at 18:45