[QGLWidget] Cannot bind texture

[Macok]

When I call

bindTexture("./sprites/1.bmp");

bindTexture("./sprites/1.bmp");

To copy to clipboard, switch view to plain text mode 

I get this warning on output:

QGLContext::bindTexture(): not a DDS image file.

and texture doesn't appear.
But when I call

QPixmap pixmap("./sprites/1.bmp");
bindTexture(pixmap);

QPixmap pixmap("./sprites/1.bmp");
bindTexture(pixmap);

To copy to clipboard, switch view to plain text mode 

everything works fine.
What's wrong?