Who to use backup with triggers in sqlserver2008

Question

Hi...

I have a table (Cycle)...

Then I create a trigger

**

alter trigger AnyName on Cycles
for insert,update,delete
AS
BACKUP DATABASE medrepcrm TO  DISK = N'C:\medrepcrm.bak' WITH NOFORMAT, INIT,  NAME = N'pcrm-Full Database Backup', SKIP, NOREWIND, NOUNLOAD,  STATS = 10
GO

**

but,when I insert,update or delete in cycle table that lead to error...

**

Msg 3021, Level 16, State 0, Procedure AnyName, Line 8 Cannot perform a backup or restore operation within a transaction. Msg 3013, Level 16, State 1, Procedure AnyName, Line 8 BACKUP DATABASE is terminating abnormally. The statement has been terminated.

**

what can i do ?