I am just finishing up on a Helles Lager that I have brewed often. The problem with Lager Yeast is that you need a lot of strong viable yeast. Otherwise, it will stall right out of the gate and bacteria will overpower the wort before the yeast can gain some motion. In my recipe I used 3/4 gallon starter using a stir plate with two vials of good healthy yeast. It still took a while to start up.
You have to be aware that yeast are sensitive. Shipping, storage and temperature changes can kill the poor little critters. You may have a bad batch of yeast that couldn't do the job, which gave the bacteria an opportunity to feast on your sugary wort. Also, keep in mind, you have to have some very sanitary equipment to keep out as much bacteria as possible. Check out my recipe and brewing process:
At this point it's ruined if that growth is really bacteria. The Helles/Maibock is a light beer and any errors made during the brewing and fermentation will show up in a big way. That's very apparent with mold growth and no startup in fermentation.
PS: That said: Are you sure that the mold growth isn't just fermentation? Put up some close up pics so everyone can see it. I wouldn't worry about the gravity readings just yet, it's a very slow process and takes a lot of patience, unlike an Ale.
Try Again, Cheers