c# - Error when trying to connect to the database EF and SQL Server -

i'm doing test new host, , facing problem connection database.

i have same project going on hosting , running on sql server 2005.

but new hosting, sql server 2012 , when trying page fetches data database returns error:

a network-related or instance-specific error occurred while establishing connection sql server. server not found or not accessible. verify instance name correct , sql server configured allow remote connections. (provider: sql network interfaces, error: 26 - error locating server/instance specified)

connection string:

<connectionstrings>     <add name="erpcontext"           connectionstring="data source=sql5003; initial catalog=db_99c4e9;user id=db_99c4e9;password=senha;"           providername="system.data.sqlclient" /> </connectionstrings> 

erpcontext:

    public class erpcontextuser : dbcontext     {         public dbset<usuarioativacao> usuarioativacao { get; set; }          public erpcontextuser() : base("conexaoerp")         {             database.setinitializer<erpcontextuser>(null);         }          protected override void onmodelcreating(dbmodelbuilder modelbuilder)         {             modelbuilder.entity<usuarioativacao>().totable("usuario");         }     }      public class erpcontext : dbcontext     {         public dbset<empresa> empresa { get; set; }         public dbset<pessoa> pessoa { get; set; }         public dbset<usuario> usuario { get; set; }         public dbset<usuarioacesso> usuarioacesso { get; set; }         public dbset<simnao> simnao { get; set; }                 public dbset<sexo> sexo { get; set; }         public dbset<tipopessoa> tipopessoa { get; set; }         public dbset<unidademedida> unidademedida { get; set; }          public erpcontext()             : base("conexaoerp")         {             database.setinitializer<erpcontext>(null);         }          protected override void onmodelcreating(dbmodelbuilder modelbuilder)         {             modelbuilder.entity<empresa>().totable("empresa");             modelbuilder.entity<pessoa>().totable("pessoa");                         modelbuilder.entity<usuario>().totable("usuario");             modelbuilder.entity<usuarioacesso>().totable("usuarioacesso");         }     } 

seem need change name erpcontext conexaoerp in web.config