glGet with GL_MODELVIEW_MATRIX won't work

OpenGL OpenGL: Basic Coding
1

Here is a part of my code.
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glGetFloatv(GL_MODELVIEW_MATRIX, mvmatrix);
glMultMatrixd(matrixd);
glGetFloatv(GL_MODELVIEW_MATRIX, mvmatrix);

I get the model matrix successfully in the first glGet, but in the second glGet, I get the same matrix with the first one. But my matrixd is not an identity matrix, and I’ve checked with glGetError. I am really confused.