terraform vsphere data source fail

config.tf

data "vsphere_datacenter" "datacenter" {
  name = "Sample DC"
}

create_vm.tf

module "app_vm" {
  source = "../resource"

  ...
  datacenter = "${data.vsphere_datacenter.datacenter.id}"
  ...
}

resource.tf

resource "vsphere_virtual_machine" "atlanta_linux_box" {
  ...
  datacenter = "${var.datacenter}"
  ...
}