PopSearch installation

[Jeffrey Mutonho]

I'm trying to install PopSearch    , but  make is dying with the
following error message :

DirectoryParserUtilities.cc: In member function `std::string
   DirectoryParserUtilities::addEmail(const std::string&, const std::string&,
   const std::string&)':
DirectoryParserUtilities.cc:188: `sleep' undeclared (first use this function)
DirectoryParserUtilities.cc:188: (Each undeclared identifier is reported only
   once for each function it appears in.)
make[2]: *** [DirectoryParserUtilities.lo] Error 1
make[2]: Leaving directory `/home/maven/popsearch/popsearch-0.3.0/src/build'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/maven/popsearch/popsearch-0.3.0/src'
make: *** [all-recursive] Error 1

What am I missing?

jeff mutonho