I've made this skript work before but when I tested this morning it didn't? Does anyone see anything that could help?

Code (Text):

1. variables:
2.    {_block1} = black glazed terracotta
3.    {_block2} = white glazed terracotta
4.    {_block3} = blue glazed terracotta
5.    {_range} = 20
6.  
7. #COAL GEN
8. every 5 seconds:
9.     loop all players:
10.         loop all blocks in radius {_range} around loop-player:
11.             if loop-block is {_block1}:
12.                 drop a coal at loop-block's position
13.  
14. #IRON GEN
15. every 5 seconds:
16.     loop all players:
17.         loop all blocks in radius {_range} around loop-player:
18.             if loop-block is {_block2}:
19.                 drop a iron ingot at loop-block's position
20.  
21.  
22. #DIAMOND GEN
23. every 5 seconds:
24.     loop all players:
25.         loop all blocks in radius {_range} around loop-player:
26.             if loop-block is {_block3}:
27.                 drop a diamond at loop-block's position
28.  
29.  
30. on first join:
31.     set join message to "Welcome %player% to Darkminey!"
32. on join:
33.     player has played before
34.     set join message to "Welcome back, %player%!"