Did you open a bleeder screw or disconnect a brake line as to need bleeding? If you did not open the fluid circuit at any time, the rubber flex hose is twisted, remove caliper and straighten hose out, clean out bleeder screw.
RepairPal Certified shops can diagnose and repair your 1999 Mercedes-Benz E300. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.