EUNKNOWN: Native target failed to build

I’m triyng build to android but it gets some errors:

-set-mode-check:

-set-debug-files:

-check-env: [checkenv] Android SDK Tools Revision 24.0.2 [checkenv] Installed at C:\Program Files (x86)\Android\android-sdk

-setup: [echo] Project Name: NewsFeed [gettype] Project Type: Application

-set-debug-mode:

-debug-obfuscation-check:

-pre-build:

-build-setup: [getbuildtools] Using latest Build Tools: 23.0.0 [echo] Resolving Build Target for NewsFeed…

BUILD FAILED C:\Program Files (x86)\Android\android-sdk\tools\ant\build.xml:542: Unable to resolve project target ‘android-19’

Total time: 0 seconds (exit code: 1)

: EUNKNOWN: Native target failed to build

Build completed in 26.08 seconds 0 Warning(s) 1 Error(s)

Error Summary

: EUNKNOWN: Native target failed to build FATAL ERROR: Build failed.