ID2D1HwndRenderTarget::Resize FAILED

while( 1 ) {
    ...
    pdev->Resize( D2D1::SizeU( unclientwidth, unclientheight ) );
    pdev->Clear( &ImplColorD2D1( D2D1::ColorF(0.0, 0.0, 0.00) ) );
}

I want to update the size of the render target the same size with the window client size.

Code above is all my opertions where I call ID2D1HwndRenderTarget interface. Even there's no opertaion to render anything.

I tried to call ID2D1HwndRenderTarget::Resize but it returned the code below

D2DERR_OUTSTANDING_BITMAP_REFERENCES

0x88990022

The operation cannot complete while there are outstanding references to the target bitmap.

From MSDN

I tried to find what's going on for hours but it all come to nothing.

What happened in the world? Please reply me if you have any ideas.

Thanks in advance.