when i run sudo apt-get install eprints ..follwing error is displayed

Reading package lists... Done
Building dependency tree      
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

i successfully completed the sudo apt-get update

how can i fix it

regards

aditya