No main-line or primary module specified
You’ve attempted to create a .dbr file without specifying a main routine. Specify a file that contains a main routine or create an ELB.
If you encounter this error when building a Multiple Mainline project in Visual Studio, make sure that each of the source files contains a main routine. Visual Studio will try to compile and link each of the source files in a Multiple Mainline project into its own program and will throw this error if any source file lacks a mainline (for example, if it's just a subroutine or function).