You might want to test the known good bulb from the other side first to make sure your ballast isn't the root cause.

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2002 Carbon Black BMW ///M5 (Black Extended Leather, Anthracite Alcantara, Titanium Trim, M-Audio with Enhanced Bass, PDC) and various mods

2003 Sapphire Black BMW X5 (Dakota beige leather, heated front and rear seats, Light Poplar Trim, power adjustable rear seats, sunshades, running boards, MK4 Nav,DSP)