ODBC - insert on a linked table failed

I have the Front_end in the MS-Access and the database is on theserver. Have connected the database with the ODBC connecter.

I have attached the sub-form under the form. and assign the TAb. while adding the new Record, when I clicked on the form it is showing me this error ODBC - insert on a linked table failed. (Error 3155). The error just pops out while clicking every on the table. even when I click on the close button, before closing the window this popup comes ODBC - insert on a linked table failed. (Error 3155). Dont know how to rid off from this trouble shoot.

Important Note:

1. The Main form has the table linked - tblInvoices ( This table is the parent table of the tblInvoiceDetails.

2. SubForm under the main form has the Linked table - tblInvoiceDetails - this table is linked with the parent table tblInvoices.

3. When i m entering the some data on main Form, and then press enter to go under Subform
   then this popup appears ODBC - insert on a linked table "tblInvoices" failed.

4. tblInvoices has a large amount of data ~1m rows.

5. tblInvoiceDetails has a large amount of data ~2M rows.

6. In tblInvoiceDetails there is the foriegn key which is refer to the tblInvoices Unique key.

Have Tried:

1. Have recreated the database with the new tblInvoices and tblInvoiceDetails with limited rows.
2. In tblInvoices and tblInvoiceDetails we have added and checked the primary key in each table.

Screen Shots:

If anything you professionals required then please let me know. will share you.

Thank you. for your help.