Error with Berkeley DB and display tiles

[samtux]

Hi, I am creating a cache with Berkeley DB, mapcache_seed successfully generate tiles, but when it display the tiles, reports the following error:

"failed to aquire connection to bdb backend: unknown error"

how can I fix or connect to the Berkeley DB?. I'm using Ubuntu Server 12.05 and Berkeley 5.1 (libdb5.1)

Thanks,

SamTux