Full Database Backup Issue

I am facing backup issues in my environment.

OS - Windows Server 2008 R2 
SQL - SQL Server 2008 R2
Netbackup Master Version - 7.5.0.7
Client Master Version - 7.5.0.1

Issue 1 : Database logs backups are runing fine but full database backups are not working. Full keeps runing fails.
Issue 2 : Backup failed at veritas end but SQL Job keeps runing in hung state. We need forcibly stopped the SQL Agent Backup job each time.

Things we tried :-
1)  Port are checked
2) Access for veritas netbackup account at OS & SQL Server
3) Antivirus exclusion for netbackup process

Please suggest.