On one of my views I need an index but the index keeps vanishing after I have created it.

It is a small view. I create the view then create the index with

INDEX on seq TAG seq

This works with no error messages but no index results afterwards.

SET ORDER TO TAG SEQ produces no error message.

the ORDER() command returns an empty string

Using SET to check the data environment does indeed show there is no index on the view.

Is a disk presence required before I can create an index? because I notice that the view only appears in memory and not on disk. This might be my problem.

If so how do I force a disk presence since it does not appear in the view designer.