A default DbContext context must exist, or a context factory must be provided

I'm getting the following error while performing "Bulk Insert" using EntityFramework extensions.

_indnCon.BulkInsert(_DataToTrans, operation => operation.IncludeGraph = true); 

Exception occurs in the above line and here is the exception.

A default DbContext context must exist, or a context factory must be provided (EntityFrameworkManager.ContextFactory). This setting is required for some features like IncludeGraph.

Here I'm passing the Connection String to the DBContext manually.

using (InsightDataContext _indnCon = new InsightDataContext(_connectionString))

Can anyone help?