New Field in Existing Form is not showing up!

New Field in Existing Form is not showing up!

Hi 

Can anyone help please?  I'm new to Zoho and my husband created my database and forms, but I've added a new field to the form.  When I want to create a relationship from another form to this new field, it doesn't show up in the field listings?  Very strange considering I can see it in the Form and the reports too.  

Any ideas?

Many thanks, Nicky