modelcheck with and without compression gives different answers

ltsmin/modelcheck: emptiness check gives different answers while using this kind of compression should never impact the result...

./ltsmin/modelcheck -e telephony.2.dve 'XF"User_0.error_state" <-> ("User_0.busy" -> ("User_0.dialing" & "User_1.error_state"))'

51827 unique states visited

0 strongly connected components in search stack

200325 transitions explored

23529 items max in DFS search stack

0 pages allocated for emptiness check

no accepting run found

./ltsmin/modelcheck -z -e telephony.2.dve 'XF"User_0.error_state" <-> ("User_0.busy" -> ("User_0.dialing" & "User_1.error_state"))'

1322 unique states visited

10 strongly connected components in search stack

4678 transitions explored

1117 items max in DFS search stack

0 pages allocated for emptiness check

an accepting run exists (use -C to print it)