SQLite3 Insert statement error, but error message blank? - c++

Question

I'm working on a basic program to learn how to use SQLite3; a user gives input on a song they'd like to add to a SQLite database, and it is inserted. As far as I can seen, the insert statement I'm generating- while not pretty- is a valid statement, but once it reaches my queryDatabase() function it enters the error clause. It prints "Error in execution: ", but when it moves on to errmsg, it seems to enter into a state where nothing happens/no actual error message is printed until I enter .quit. I've tried altering the print line like cout << "ERROR EXECUTING SQL: " << errmsg << "End";, and "End" never prints.
Here is the section of code that calls the queryDatabase() function/passes the command string. args refers to a vector that contains the user input:
string sqlq;
sqlq = "INSERT INTO songs (sid, title, composer) VALUES(";
sqlq.append(args[2]); sqlq.append(", "); sqlq.append("\'"); sqlq.append(args[3]); sqlq.append("\'"); sqlq.append(", "); sqlq.append("\'"); sqlq.append(args[4]); sqlq.append("\'"); sqlq.append(");");
data.queryDatabase(sqlq);
and here is the queryDatabase() function:
sqlite3 *db;
char * errmsg = 0;
int rc;
void Data::queryDatabase(string queryString){
if(queryString.empty()) return;
const char * sqlQuery = queryString.c_str();
rc = sqlite3_exec(db, sqlQuery, callback, (void *) data, &errmsg);
if( rc != SQLITE_OK) {
cout << "Error in execution: " << errmsg;
} else {
cout << "\nSQL QUERY SUCCEEDED\n";
}
}
Both queryString and sqlQuery print INSERT INTO songs (sid, title, composer) VALUES(1905, 'Anti-rage', 'Emperor X'); which as far as I know is a valid command, as copy and pasting this when working direct in the database from terminal results in the song being added. Why might this not be inserting correctly, and why am I not being given an error message?
MODIFIED FOR MORE INFO:
Here's the callback
static int callback(
void * data, //pass through data provided to sqlite3_exec() [4th argument]
int argc, //# of cols in table row
char ** argv, //array of strings representing table row values
char ** azColName //array of strings representing column names
){
for (int i=0; i<argc; i++){
cout << argv[i] << ", ";
}
cout << "\n";
return 0;
}