Are you committing the record? If you have the script debugger open, are their any script triggers firing. Also, what parameters are in your validation tab?
my understanding is that clicking on layout after changing any data ( not clicking another field ) is one way to commit
when I do that or run a "commit & refresh" script I get this msg. The field is a job description on a job record , not a related field and is receptive to editing and entry ? how can it be that its "not available" ?
no scripts are firing, doesn’t seem to matter what field I apply "Not Empty" requirement .... always get "not available on this layout"
If I apply numeric range only or numeric only it functions properly.
So your field validation IS "responding" or you would not get this message. You will get this message if the field responsible for the validation error message is not present on the current layout since you then cannot use the current layout to correct the error-at least via a manual edit of the data.
So presumably, the description field is not present on the current layout at the time when you get this validation error message.