How to change walllpaper in c using winapi?

I tried thi开发者_运维问答s but it does not work

LPWSTR test = L"C:\\Users\\Default\\wallpaper.png";
SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, test, SPIF_UPDATEINIFILE);

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The documentation says that the file must be a bitmap (or, possibly, a JPG).