As I stated in your other similar thread:
Still I have The message �??maximum number of connections to instance exceeded"
It looks like you have Personal ArcSDE technology (aka. ArcSDE for SQL Server Express) and it only supports 3 concurrent users, one of which can be an editor. If you would like to enable concurrent editing with 3 or more users, you will have to upgrade to Workgroup ArcSDE technology (aka. ArcSDE for SQL Server Express).
Hope this helps,