Linker error while connecting static library with DLL

[forstudy3]

I had defination as well.This static library builds succesfully,but when trying build another C++ DLL throws linker error.Here is defination of SetLogger().

log4net::ILog^ CustomLog::SetLogger()
{
String^ str = "CustomLoger";
CustomLog::m_logger = log4net::LogManager::GetLogger(str);
return CustomLog::m_logger;
}

Any thoughts??