fifo deletion problem..

I have unix sco server. I have created one application for client server communication. On this I have creted some fifos/pipes.
The reader.123 fifo is used by one process for reading and writing. I haven't deleted that fifo. But ls or find command doesn't show it. It is giving error as file or directory does not exist.

So I want to create that fifo again. But while creating using mkfifo it is giving error as file already exist. This is as follows:

$ ls -ltr reader.123
$ls: reader.123 not found: No such file or directory (error 2)
$ find reader.123
$cannot found reader.123: No such file or directory (error 2)

$ mkfifo reader.123
$mkfifo:cannot make fifo: reader.123 :file exists (error 17)

I am surprising by seeing this 2 different behaviours. If file is not present then why i am not able to create it again.

please help urgently.
Thanks in advance.

Probem is now some extent is solved.
I thinked that for such corrupted files inodes might have corrupted or links in super block may be corrupted. This problem was related with filesystem.

So I ran the command fsck in the single user mode. The command was asking about to recover those files. By giving correct options I recoverd the filesystem. Now problem is resolved to some extent but not fully.