Madhur,
First think is to need to identify where the problem exists like a) SAP backend configuration for document management and /syclo/configpanel configuration settings b) push port settings c) SMP server not reachable from SAP ( specify IP address --if FQDN didn't work. d) check push queue status from /syclo/admin and so on so forth.
You need to look at below blog and make sure that you have applied all the OSS notes in your system .
You can also execute BAPI on SAP side which is called by Agentry to cross check if required document is downloaded. if document is not download then check SAP configuration else check why SMP 3.0 is not reachable from the SAP side.
Thanks,
Manju - SAP RIG