1st, check the fuse for the pump. I replaced my pump before realizing the fuse was blown.

Only use the fluid type specified in the manual. I'm sure it calls out the same Zerex G05 as Mercedes. I only found it at NAPA (besides the over-priced dealer). It is a special type - HOAT (Hybrid Organic Acid Technology). Don't mess with other formulas as the properties can cause damage to the internal system over time.