Why Build fails to trigger in Openshift

Issue

• After creating a new application the build is not automatically triggert when using STI with DockerImage strategie.

"strategy": {
          "type": "Source",
          "sourceStrategy": {
            "from": {
              "kind": "DockerImage",

• The build will only be triggered when using imagestreams

"strategy": {
          "type": "Source",
          "sourceStrategy": {
            "from": {
                 "kind": "ImageStreamTag",
                 "namespace": "openshift",
                 "name": "php:5.5"
               }