asp.net - Why does Velocity lose session after only a few minutes? -

I have set up season management with a distributed distributed cache. I have 3 servers hosting cache and

  New-Cash Sessions - Seconds 1 TTL 1440  

and the following is the .config file in my web.

  & amp; Lt; Section name = "datacash client" type = "Microsoft.Data.Caching.DataCacheClientSection, & amp; #xD; & amp; #xA; cacheBaseLibrary" permission = "correct" permissions = "everywhere" /> & Lt; Session Location Mode = "Custom" Custom Provider = "Velocity" & gt; & Lt; Providers & gt; & Lt; Add name = "velocity" type = "Microsoft.Data.Caching.DataCacheSessionStoreProvider" cacheName = "session" /> & Lt; / Providers & gt; & Lt; / SessionState & gt;  

Any help would be appreciated.