swift build error

I had installed swift in my cloud machine, which is ubuntu 14.04.
run "swift" command is ok, I can use REPL.
But when I create a package code followed by official tutorial, create a
empty content file named Package.swift, and a source code file, just one
line code:print("hello")
when I run "swift build" command, the error occurs:
swift-build: exit(127):
["/home/ubuntu/tools/swift/swift-2.2-ubuntu14.04/usr/bin/swiftc",
"--driver-mode=swift", "-I",
"/home/ubuntu/tools/swift/swift-2.2-ubuntu14.04/usr/lib/swift/pm", "-L",
"/home/ubuntu/tools/swift/swift-2.2-ubuntu14.04/usr/lib/swift/pm",
"-lPackageDescription", "/home/ubuntu/code/hello/Package.swift"]

Is there something wrong?