No idea why you would need a "One to One" relationship. Pretty rare to do that. Can you explain what fields you are joining on? What are the primary and foreign keys? And what indices have you applied to the table? My guess is you are trying to establish relationship on a PK that is not unique and thus not indexed. Or as you said you have a cascade delete linked to a primary key, which I also doubt you can do. You could also just show a screen shot.
First let me thank both respondents for your replies. Obviously what I am doing is a bit different, so;
A bit of history to get things straight.
I have just completed the job of photographing some 12,000 specimens for a local herbarium. In the process I noticed the database was in complete disarray so decided to clean it up. The database has 12,000+ records and about 90 fields, most of which are unique to a particular specimen so the opportunity for smaller, related, tables is limited. Each record is defined by a unique "Accession Number" that is manually generated and may, or may not, have a decimal point, hence the one to one. That was Access's doing, by the way, not mine. I have split the main table into three sections, and related them, one to many, by converting the ID key to Replication ID. I have now created three linked forms to facilitate data entry, the first of which will have drop-downs for data consistency with some fields automatically filled with date etc. The data in the other forms is specimen specific so must be entered individually
My next little problem is how to reference data from table "A" into form "B". I need a new accession number to be transferred from a new record in table "A" to the appropriate fields in tables "B" and "C".
My journey into Access is just beginning. My knowledge of VBA is nil although I have some recent experience with java and Clipper / DB3 many years ago so am familiar with the basic concepts of programming.
A bit long winded but hopefully clears things up.
John
Old I may be but this dog thrives on new tricks.