Coldfusion session timing out too soon?

I have coldfusion 10 installed as our main server. I am using sessions to store some information and have set sessiontimeout=#CreateTimeSpan(0,0,45,0)# in the application file but for some reason the session is timing out way before 45 mins - around 10 mins. Is there a reason for this? I thought having the timeout in the application file would overwrite anything set in the coldfusion admin. Is this not true?

Thanks