请教calibre 的lvs错误。

反向器 的lvs report文件如下：
Error:    Power net missing in layout. Ground net missing in layout.
LAYOUT CELL NAME:         123
SOURCE CELL NAME:         123
--------------------------------------------------------------------------------------------------------------
INITIAL NUMBERS OF OBJECTS
--------------------------
                Layout    Source         Component Type
                ------    ------         --------------
Nets:                   4         4
Instances:          1         1         MN (4 pins)
                             1         1         MP (4 pins)
                ------    ------
Total Inst:           2         2
NUMBERS OF OBJECTS AFTER TRANSFORMATION
---------------------------------------
                Layout    Source         Component Type
                ------    ------         --------------
Nets:                 4         4
Instances:          1         0    *    MN (4 pins)
                             1         0    *    MP (4 pins)
                             0         1    *    INV (2 pins)
                ------    ------
Total Inst:           2         1
       * = Number of objects in layout different from number in source.
其中'Power net missing in layout. Ground net missing in layout.'是什么错误,
没有全局变量，怎么来的电源和地节点呢？
另外，INITIAL NUMBERS OF OBJECTS中，layout和source很匹配，而NUMBERS OF OBJECTS AFTER TRANSFORMATION之后就不匹配了呢？
电路网表如下：
          .SUBCKT 123 gnd in out vdd
          *.PININFO gnd:B in:B out:B vdd:B
          MPM1 out in gnd gnd nmos_5p0 W=1u L=500n M=1
          MPM0 out in vdd vdd pmos_5p0 W=1u L=500n M=1
          .ENDS
版图网表如下：
          * SPICE NETLIST
          ***************************************
          
          .SUBCKT m1_T$$179728428
          ** N=1 EP=0 IP=0 FDC=0
          .ENDS
          ***************************************
          .SUBCKT 123
          ** N=13 EP=0 IP=4 FDC=2
          M0 4 3 2 2 nmos_5p0 L=5e-07 W=1e-06 AD=8.5e-13 AS=8.5e-13 PD=3.7e-06 PS=3.7e-06 NRD=0.85 NRS=0.85 m=1 $X=-5200 $Y=-2325 $D=19
          M1 4 3 1 1 pmos_5p0 L=5e-07 W=1e-06 AD=8.5e-13 AS=8.5e-13 PD=3.7e-06 PS=3.7e-06 NRD=0.85 NRS=0.85 m=1 $X=-5200 $Y=2625 $D=20
          .ENDS
          ***************************************
两网表挺匹配看不出什么错误.