glReadPixel returns wrong buffer pixels

Hello,

I tried to extend a qt existing example on Qt Creator from Examples tab.The example is using QOpenglFrameBufferObject and rendering two separate FBOs, one to use for display and one to use for rendering. What I did is to add some gl functions to create a render buffer to save qml screen.So following is what I added to existing code:

////////////////////////////////////////////////////////////////////////////////////////////////
GLuint renderBuffer;
GLuint frameBuffer;
int rowPack;

glGetIntegerv(GL_PACK_ALIGNMENT, &rowPack);
qDebug() << "Row pack"<< rowPack;

int mWinWidth = 1280;
int mWinHeight = 720;

glGenRenderbuffers( 1, &renderBuffer );
glBindRenderbuffer( GL_RENDERBUFFER, renderBuffer );
glRenderbufferStorage( GL_RENDERBUFFER, GL_RGB, mWinWidth, mWinHeight );
glBindRenderbuffer(GL_RENDERBUFFER, context->defaultFramebufferObject()); //mwindow->openglContext()->defaultFramebufferObject());

if (glGetError()==GL_NO_ERROR)

{ qDebug() << "Render buff storage is OK" << glGetError(); }

else

{ qDebug() << "Render buff storage error is " << glGetError(); }

glGenFramebuffers( 1, &frameBuffer );
glBindFramebuffer( GL_FRAMEBUFFER, frameBuffer);
glFramebufferRenderbuffer( GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderBuffer);

if( glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)

{ qDebug() << "Framebuffer error is " << glGetError(); }

else

{ qDebug() << "Framebuffer is OK" << glGetError(); }

glBindFramebuffer( GL_FRAMEBUFFER, context->defaultFramebufferObject() );

int size = mWinWidth * mWinHeight *3;
glPixelStorei(GL_PACK_ALIGNMENT, 1);

int* buffer = new int[size];
glReadPixels( 0, 0, mWinWidth, mWinHeight, GL_RGB, GL_UNSIGNED_BYTE, buffer );

QImage hell((uchar*)buffer,mWinWidth,mWinHeight,QImage::Format_RGB16);
if (!hell.save("hell.png"))

{ qDebug() << "hell on image save"; }

else

{ qDebug() << "hell is " << hell; }

/*FILE *out = fopen("tga_file", "w");
short TGAhead[] =

{0, 2, 0, 0, 0, 0, 1280, 720, 16}

;
fwrite(&TGAhead, sizeof(TGAhead), 1, out);
fwrite(buffer, size, 1, out);
fflush(out);
fsync(fileno(out));
fclose(out);*/
delete [] buffer;

//QImage fboImage (m_renderFbo->toImage(false));
//QImage image = fboImage.convertToFormat(QImage::Format_RGB16);

glDeleteRenderbuffers(1,&renderBuffer);
renderBuffer = 0 ;
glDeleteFramebuffers(1,&frameBuffer);
frameBuffer = 0;
glPixelStorei(GL_PACK_ALIGNMENT, rowPack);

////////////////////////////////////////////////////////////////////////////////////////////////

so from above code section glReadPixel returns wrong buffer.

If I commented out the two lines after deletion of buffer:
QImage fboImage (m_renderFbo->toImage(false));
QImage image = fboImage.convertToFormat(QImage::Format_RGB16);

all the time glReadPixel returns correct buffer and creates correct png image.

I am attaching the project as a zip file into attachments.
Could you please check the issue ?

Regards