start_test_server_in_background report failed to connect to socket 'tcp:7102'

[mayfu]

I follow https://github.com/calabash/calabash-android-server to execute build for test project and tests
$ ./run-tests.sh
it report:

Scenario: Running the unit test # features/unittest.feature:2
Then I install the app # features/steps/shared.rb:1
Then I start the app # features/steps/shared.rb:5
App did not start see adb logcat for details (RuntimeError)
/calabash-android-server/server/integration-tests/calabash-android/ruby-gem/lib/calabash-android/operations.rb:743:in block in start_test_server_in_background' /calabash-android-server/server/integration-tests/calabash-android/ruby-gem/lib/calabash-android/retry.rb:10:in block in retry'
/calabash-android-server/server/integration-tests/calabash-android/ruby-gem/lib/calabash-android/retry.rb:8:in times' /calabash-android-server/server/integration-tests/calabash-android/ruby-gem/lib/calabash-android/retry.rb:8:in retry'
/calabash-android-server/server/integration-tests/calabash-android/ruby-gem/lib/calabash-android/operations.rb:742:in start_test_server_in_background' /calabash-android-server/server/integration-tests/calabash-android/ruby-gem/lib/calabash-android/operations.rb:152:in start_test_server_in_background'
./features/steps/shared.rb:7:in /^I start the app$/' features/unittest.feature:4:in Then I start the app'

I use "adb logcat -d", it print:

=============
8-27 17:57:56.629 2075 2075 D ImsResolver: maybeAddedImsService, packageName: sh.calaba.unittester.test
08-27 17:57:56.637 2075 2075 D CarrierSvcBindHelper: No carrier app for: 0
08-27 17:57:56.645 2350 2350 E adbd : failed to connect to socket 'tcp:7102': Connection refused
08-27 17:57:56.647 2350 2350 E adbd : failed to connect to socket 'tcp:7102': Connection refused

what's wrong?