I have an IDM connection between two trees.

One tree (A) is IDM 3.0.1, the other one (B) is 3.5.

Today I experienced a weird problem.

After connecting our telephony system to the A-tree we populated the
Telephone Number attribute on users. The changes synchronized with the B
tree but after the change was complete and the <status> was sent back to
tree A the driver said:

15:35:17 61101BB0 Drvrs: XXX ST: Re-reading associations in case they
were changed by previous event processing
15:35:17 61101BB0 Drvrs: XXX ST: Subscriber processing modify for
15:35:17 61101BB0 Drvrs: XXX ST: No existing association, converting
<modify> to <add>.
15:35:17 61101BB0 Drvrs: XXX ST: Reading relevant attributes from

The driver the proceeded to send an <add> document to the B tree which
triggered a matching policy which of course found a match.

The add document had two association elements:

<association state="pending"></association>

The driver on the B tree: (PT)
Missing valid association or dest-dn

The match produced:

Code(-9063) Object matching policy found an object that is already

Under which circumstances does the driver re-read the associations and why?

What could cause it not to find an existing association?
It clearly sends the association with the <add>