求解决:全编译都通过，但用singletap编译不通过

Error: Found I/O cells that do not connect to top-level pins or have illegal connectivity
        Error: Output I/O cell "pre_syn.bp.data_0_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_1_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_2_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_3_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_4_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_5_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_6_~output" in partition "Top" driving ""
        Error: Output I/O cell "pre_syn.bp.data_7_~output" in partition "Top" driving ""
分析综合，全编译都通过，但用singletap编译不通过，请问这是怎么回事???