Warning: The structure contains misaligned fields

Is anybody can tell me what is wrong with this? Is this a fatal error
in fortran?
      Thanks!
-------------------------------
    module test
    implicit none

    type :: ccc
        sequence
        private
        logical :: is_null=.true.
        real(8):: A0=0d0,B0=0d0, Lambda0=0d0, H0=0d0
     end type ccc
    end module test
-------------------------------
The compile says:

  Warning: The structure contains one or more misaligned fields.
[CCC]