qt signal undefined reference error

I have a class server for which I have created a signal joined(QString name). I call it in a function called join(QString name), however I'm getting the error Server.o: In function `Server::join(QString)': Server.cpp:(.text+0x48): undefined reference to `Server::joined(QString)' collect2: ld returned 1 exit status This is what my header file looks like: ``` #ifndef SERVER_H #define SERVER_H #include <QString> #include <mqueue.h> #include <QVector> #include <QStringList> #include "../src/messages.h" class Server { public: Server(); void start(); private: void join(QString name); char buf[MSG_SIZE], msgSend[MSG_SIZE]; QVector<mqd_t> mq_external; QVector<QString> users; mqd_t mq_central; struct mq_attr attr; signals: void joined(QString name); }; #endif // SERVER_H ``` and this is my cpp file: ``` #include "Server.h" using namespace std; Server::Server() { } void Server::start(){ attr.mq_maxmsg = 100; attr.mq_msgsize = MSG_SIZE; attr.mq_flags = 0; mq_unlink(CENTRALBOX); mq_central = mq_open(CENTRALBOX, O_RDONLY | O_CREAT, S_IRWXU, &attr); while(1) { int tempMsgVal = mq_receive(mq_central, buf, MSG_SIZE, 0); if(tempMsgVal != -1){ QString tempS = buf; QStringList tempSL = tempS.split(":"); if(tempSL.size() == 2 && tempSL.at(0) == "started") { int x = 0; bool exists = false; for(int i = 0; i < mq_external.size(); i++) { x = QString::compare(tempSL[1], users.at(i), Qt::CaseInsensitive); if(x == 0) { exists = true; break; } } if(!exists) { sprintf(buf,"joined"); QString tempS1 = tempSL[1] + "new"; QByteArray byteArray = tempS1.toUtf8(); const char* tempr = byteArray.constData(); mqd_t tempMQ = mq_open(tempr, O_RDWR); int tempI = mq_send(tempMQ, buf, strlen(buf), 0); } else { sprintf(buf,"invalidname"); QString tempS1 = tempSL[1] + "new"; QByteArray byteArray = tempS1.toUtf8(); const char* tempr = byteArray.constData(); mqd_t tempMQ = mq_open(tempr, O_RDWR); int tempI = mq_send(tempMQ, buf, strlen(buf), 0); }//Endelse }//Endif }//Endif }//Endwhile } void Server::join(QString name) { emit joined(name); } ```