help: Shared memory init error

I am running Informix 7.1e and tried to restore my database from a Unix backup tape. I tried to restore "users/informix" and "dev/yponline". Now when i try to bring my database online I get on the following error message "oninit: Fatal error in shared memory initialization". The message log file is as follows: Could not disable priority aging: aging errno =2 DR: DRAUTO is 0 (Off) warning: chunk timestamps are invalid I/O error, Primary chunk 'dev/yponline' -- Offline (sanity) INFORMIX-OnLine Stopped mt_shm_remove: WARNING: may not have removed all/correct segments Could anyone offer me some advice? Thanks