no log backups: only full backups

I cheked everything .

1) no active transactions

2) log_reuse_wait=log backup

we have a dialy backup at 10 pm

I got a mail automatically when ever the space issue occurs

I have only this drive, this drive is only for sql server databases

Thanks for ur reply

what u said is good for me, any other ways

thanks for the information

can you please tell me briefly

sql server 2005 service pack3

i already installed ssis but the same problem has occured

first step of the maintenance plan gets that error.