You can maybe find this error message when you using a clustered SQL Server.

You cannot create/delete a new model (from AX client or from AxUtil.exe tool) but can still make a listing of all model.

In fact, all writing modification cannot be done.

 

The main solution : http://ax4dev.wordpress.com/2013/07/17/the-network-path-was-not-found-with-a-clustered-sql-server/