C-Isam, NFS Mounted Files

Some of our customers has 2 Workstations A and B. On A are the C-Isam Files and a process, which writes and reads to these files. On B there is one more process, who writes and reads on the files on A. The Files are NFS-mounted, but it seems, that the rows, written by B, don't come on their place in the Files on A, because (perpaps) the process on machine A is locally working on these files. Question: C-Isam and NFS-mounted files - is it ok? Any answer is a good answer (best answer: why don't they use OnLine or SE?)