NIC Teaming Slow Throughput, any ideas?

Hey guys,

We currently have 2Gig set up through NIC teaming for our backup exec setup.When we have backups running, it barely reaches 35-40% of the bandwith. 

I am using Backup Exec 2010. Has anyone else here set up NIC teaming before? What are some things that might cause slow performance? Are there any specific settings in Backup Exec that may help?

Thanks!