cannot see every face of cube while rotating

Hi guys ! I’m relatively new to openGL and today i tried to create a cube that spins. However, when i rotate it, i cannot see all it’s faces, but only a few. I figured out it’s something wrong with my camera or perspective. Here is the code i used:

	glClearColor(255,255,255,255);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(25,1,10,200);

	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	gluLookAt(20,30,50,0,0,0,0,1,0);

	glEnable(GL_DEPTH_TEST);
	glCullFace(GL_BACK);
	glEnable(GL_CULL_FACE);
	glViewport(0,0,dim,dim);
	glDepthFunc(GL_LEQUAL);

what should i add to see every face of the cube ?
The cube is drawn “by hand”, by calculating the new positions at every rotation:

struct Punct{
	double x,y,z;
};

struct Cub{
	Punct p[8];
};

Cub cube;
void rotatePoint(double &x,double &y,double angle){
	double a,b;

	a = x * cos(angle) - y * sin(angle);
	b = y * cos(angle) + x * sin(angle);

	x = a;
	y = b;
}

void rotateCubeOX(double angle){
	int i;
	for( i = 0; i < 8; i++){
		rotatePoint(cube.p[i].y,cube.p[i].z,angle);
	}
}

void rotateCubeOY(double angle){
	int i;
	for( i = 0; i < 8; i++){
		rotatePoint(cube.p[i].x,cube.p[i].z,angle);
	}
}

void rotateCubeOZ(double angle){
	int i;
	for( i = 0; i < 8; i++){
		rotatePoint(cube.p[i].x,cube.p[i].y,angle);
	}
}

inline void Quad(GLdouble* v1,GLdouble* v2,GLdouble* v3,GLdouble* v4){
	glBegin(GL_QUADS);
	glVertex3dv(v1);
	glVertex3dv(v2);
	glVertex3dv(v3);
	glVertex3dv(v4);
	glEnd();
}

void deseneazaCub(){
	double a[] = {cube.p[0].x,cube.p[0].y,cube.p[0].z};
	double b[] = {cube.p[1].x,cube.p[1].y,cube.p[1].z};
	double c[] = {cube.p[2].x,cube.p[2].y,cube.p[2].z};
	double d[] = {cube.p[3].x,cube.p[3].y,cube.p[3].z};
	double e[] = {cube.p[4].x,cube.p[4].y,cube.p[4].z};
	double f[] = {cube.p[5].x,cube.p[5].y,cube.p[5].z};
	double g[] = {cube.p[6].x,cube.p[6].y,cube.p[6].z};
	double h[] = {cube.p[7].x,cube.p[7].y,cube.p[7].z};
	glColor3f(1,0.1,0.1);
	Quad(a,b,c,d);//fata
	glColor3d(1,1,0);//galben
    Quad(c, b, f, g); // dreapta
	glColor3d(186,85,211);
    Quad(h, g, f, e); // spate
	glColor3d(205,127,50);
    Quad(d, h, e, a); // stanga
	glColor3d( 0, 1, 0 ); // verde
    Quad(d, c, g, h); // deasupra
    glColor3f(0.0f,0.0f,1.0f); // albastru
    Quad(e, f, b, a); // dedesubt
}