You may receive an "invalid credential" error when trying to sync dimensions by:

AssetAccountant™ > Register Settings > Classifications > Sync Classifications

And/or attempting to post journals.

It's not always obvious that you need to select a particular journal for Sage Intacct.

In order to do this, please go to AssetAccountant™ > Register Settings > Integrations > Configure.

This will allow you to choose the appropriate journal to post to.