SQL & Backupexec 2012

Dear all,

I can not be able to take backup for SQL server, backup exec throw this error ' The Backup Exec SQL Agent was not used to create the last full backup of this database. You must use the SQL Agent to run a full backup before you run a differential backup or transaction log backup', SQL configured is configured with full inbuilt backup mode.

Any help will be appreciated .

Thanks in advance,

Basem