Unable to compile on Ubuntu 16.04

I've compiled libecap into /opt/ecap and am attempting to compile the adapters now, but here's what I get:

Making all in src
make[1]: Entering directory `/home/nobackup/build/ecap_adapter_sample-1.0.0/src'
make all-am
make[2]: Entering directory `/home/nobackup/build/ecap_adapter_sample-1.0.0/src'
/bin/bash ../libtool --tag=CXX --mode=compile g++ -DHAVE_CONFIG_H -I../src -I/opt/ecap/include -g -O1 -Wall -Wwrite-strings -Woverloaded-virtual -pipe -pthread -g -O1 -Wall -Wwrite-strings -Woverloaded-virtual -pipe -MT ecap_adapter_async_la-adapter_async.lo -MD -MP -MF .deps/ecap_adapter_async_la-adapter_async.Tpo -c -o ecap_adapter_async_la-adapter_async.lo `test -f 'adapter_async.cc' || echo './'`adapter_async.cc
libtool: compile: g++ -DHAVE_CONFIG_H -I../src -I/opt/ecap/include -g -O1 -Wall -Wwrite-strings -Woverloaded-virtual -pipe -pthread -g -O1 -Wall -Wwrite-strings -Woverloaded-virtual -pipe -MT ecap_adapter_async_la-adapter_async.lo -MD -MP -MF .deps/ecap_adapter_async_la-adapter_async.Tpo -c adapter_async.cc -fPIC -DPIC -o .libs/ecap_adapter_async_la-adapter_async.o
adapter_async.cc: In member function ‘void Adapter::Xaction::analyze()’:
adapter_async.cc:257:13: error: ‘sleep’ was not declared in this scope
  sleep(delay); // simulate slow analysis
             ^
adapter_async.cc: At global scope:
adapter_async.cc:310:19: warning: ‘Registered’ defined but not used [-Wunused-variable]
 static const bool Registered =
                   ^
make[2]: *** [ecap_adapter_async_la-adapter_async.lo] Error 1
make[2]: Leaving directory `/home/jlay/nobackup/build/ecap_adapter_sample-1.0.0/src'
make[1]: *** [all] Error 2
make[1]: Leaving directory `/home/jlay/nobackup/build/ecap_adapter_sample-1.0.0/src'
make: *** [all-recursive] Error 1

Thank you...not sure what to do next.