not random at each execution

Your code (once I removed all the illegal signal assignments) works fine:

#  ** Note: random is :999
#     Time: 40 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :974
#     Time: 50 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :647
#     Time: 60 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :333
#     Time: 70 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :36
#     Time: 80 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :161
#     Time: 90 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :664
#     Time: 100 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :84
#     Time: 110 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :204
#     Time: 120 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :167
#     Time: 130 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :654
#     Time: 140 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :128
#     Time: 150 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :910
#     Time: 160 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :111
#     Time: 170 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :299
#     Time: 180 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :265
#     Time: 190 ns  Iteration: 0  Instance: /tester
#  ** Note: random is :699
#     Time: 200 ns  Iteration: 0  Instance: /tester