"You must populate the data of the primary key when appending between tables" <-- How?

[securitywyrm]

Hello all. I'm banging my head against a database I've inherted and don't have the authority to replace with a new properly built one. Thus I'm trying to run an append query between two tables, and get the "Cannot append 1275 record(s) due to validation rule violations" error.



My googling has resulted in the following advice on several forums from other people encountering this error: "On appending from one table to another, you must ensure that you populate the columns that makeup the primary key of the destination table." However this doesn't make sense to me, as shouldn't an autonumber field... autonumber?

To test this I created a simple database of two tables with four fields: An autonumber primary key field, and three data fields, one of which is also indexed (SSN, no duplicates). Even uploading only a single field (after removing the 'default value' in the indexed field) the autonumber continued to populate correctedly.

Can someone help me to understand what it means by having to "populate the data of the primary key"? Shouldn't I be leaving that blank and letting the primary key autonumber populate itself?

[isladogs]

Have you checked whether the PK field really is auto number?
If it is, then you leave it to populate itself and will get an error if you try to populate it yourself.
But if it isn't, you must populate it yourself.

Another possible issue is where another field is required and you haven't assigned a value to that