Access automatically makes relations on key fields case insensitive.
This is convenient to guard against data entry mistakes.
But this makes it hard to make relations if a unique id is different
from
the same character sequence in upper case.
Note how Access treats the following Account_Id's the same, causing
duplicates
00100000000mbnd
00100000000mbnD
If anyone has developed a convenient work-around for this,
please bring it to a Users Group meeting, or call
202-829-4444