OCS/Lync: Conference add-in shows wrong (old) conference ID

Hi,

We just migrated from OCS R2 to Lync. Most of our clients still use both the communicator client and the outlook conference add-in. For one particular user the Lync dialin page shows conference ID 1 (after resetting the conference ID), however when she tries to schedule a meeting outlook shows and old ID ie. 2.

How can we fix this?

Sebastiaan