Tape backup logs show either very little compression or no compression at all.
Check the Backup Exec job to ensure encryption is not enabled. Encryption it is not recommended when using hardware compression. If the data must be compressed, it is recommended to use software compression (Note: Software compression will increase server utilization). When using software compression the data is compressed first then encrypted. When using hardware compression the data is encrypted first then compressed. Encrypted data does not compress well because the data is randomized. In some cases using hardware compression with encryption will cause the data to become bigger rather than smaller.