Can you post a pic of how much lump you're using?

I light mine using starter blocks as well and have used probably close to ten different makes of charcoal without issue.

Few things to check:
a) Air flow - verify no vent holes are obstructed (bottom grate and those around the fire bowl) and the aft vent is completely open. If grilling, you can leave this fully open the entire time. If smoking, once you get a clean burn you can close this some.
b) Sufficient charcoal - doesn't take that much. If you're planning to grill for about an hour, you probably need to fill the fire bowl no more than 1/3 full.
c) I typically add my lump, then clear out a place in the middle of the grate and place my starter block there. After lighting the block, take your tongs or spatula (or by hand if you're careful) and mound the charcoal over the lot block.
d) Leave the lid up until the charcoal is burning clean. Don't focus on the temp yet. It's burning clean when the charcoal shows a grayish-ash color. (You may want to 'stir' it once usually about 10-15 minutes after you lit it.) Also, there will be little to no smoke emanating.

What follows is for grilling, not smoking (which would involve adding wood chunks and a plate setter):
e) After it's burning clean, put your grill on (I handle mine with tongs). Close the lid and fully open the top-cap. The thermometer should rise fairly quickly. If you're not careful, it will shoot right up to 500+ degF in little time.
f) Control the temp by closing the top cap and adjusting the vents on the pin-wheel.
g) I recommend letting it burn for about 5-10 minutes with everything adjusted. WARNING: If you open the lid too soon/too quickly air will be sucked in and you'll get a flare up that will singe the hair on your arm.

After this, you're ready to put the meat on.

Ceramic cookers are incredible cooking tools. very versatile and forgiving. There's a learning curve to be sure, but you'll enjoy it immensely over the years.