A few problems. Here's the top part of your .BLB.
2 1 3
SPECIAL
uu
xx
dd
1
0.000000 0.000000 0.000000
0.000000 0.000000 0.000000
COVERAGE:
0 : 2
0 : 2
0 : 6
0 : 3
0 : 6
0 : 3
See that lone number 1? That means that there is 1 collision box. The two rows of numbers below define the bounds of this collision box. Except they're all zeros. Which means your collision box doesn't exist. All tools in Blockland require a collision box to function. Your brick has none so you can't interact with it in any way.
In the coverage part the number on the left means hide (1) or do not hide (0). The number on the right is the number of studs/plates required to hide the faces. Currently your coverage is set up correctly and your quads are sorted, but nothing is being hidden because the left number is 0.