使用下面的Scala模板时出现了“未找到引擎”错误，
http://predictionio.incubator.apache.org/templates/complementarypurchase/quickstart/
我已经使用了正确的Scala版本。
有什么想法吗？
scala -version
Scala code runner version 2.11.8 -- Copyright 2002-2016, LAMP/EPFL
从模板 build.sbt
scalaVersion := "2.11.8"
日志：
[INFO] [Engine$] [info] Done updating.
[INFO] [Engine$] [info] Compiling 5 Scala sources to /home/pioEngine/MyComplementaryPurchase/target/scala-2.11/classes...
[INFO] [Engine$] [info] Packaging /home/pioEngine/MyComplementaryPurchase/target/scala-2.11/template-scala-parallel-complementary-purchase_2.11-0.1-SNAPSHOT.jar ...
[INFO] [Engine$] [info] Done packaging.
[INFO] [Engine$] [success] Total time: 25 s, completed Sep 29, 2017 5:03:02 PM
[INFO] [Engine$] [info] Including: scala-library-2.11.8.jar
[INFO] [Engine$] [info] Run completed in 127 milliseconds.
[INFO] [Engine$] [info] Total number of tests run: 0
[INFO] [Engine$] [info] Suites: completed 0, aborted 0
[INFO] [Engine$] [info] Tests: succeeded 0, failed 0, canceled 0, ignored 0, pending 0
[INFO] [Engine$] [info] No tests were executed.
[INFO] [Engine$] [info] Checking every *.class/*.jar file's SHA-1.
[INFO] [Engine$] [info] Merging files...
[INFO] [Engine$] [warn] Merging 'META-INF/MANIFEST.MF' with strategy 'discard'
[INFO] [Engine$] [warn] Strategy 'discard' was applied to a file
[INFO] [Engine$] [info] SHA-1: 694c8171bc698f340ad43074d037fc26642ffa8d
[INFO] [Engine$] [info] Packaging /home/pioEngine/MyComplementaryPurchase/target/scala-2.11/template-scala-parallel-complementary-purchase-assembly-0.1-SNAPSHOT-deps.jar ...
[INFO] [Engine$] [info] Done packaging.
[INFO] [Engine$] [success] Total time: 3 s, completed Sep 29, 2017 5:03:04 PM
[INFO] [Engine$] Compilation finished successfully.
[INFO] [Engine$] Looking for an engine...
[ERROR] [Engine$] No engine found. Your build might have failed. Aborting.
有什么想法吗？