用ansys模拟，系统提示degree of freedom solution is avai ？ 20

   怎么解决，我是用beam188单元模拟梁和柱，shell181模拟剪力墙，并且将他们的节点建立在一起，是不是不用建立约束方程或者耦合，但是不建立系统就这样报错，怎么解决

finish
/clear
/prep7et,1,beam188
et,2,shell181
keyopt,2,3,2SECTYPE,1,BEAM,RECT
SECDATE,0.5,0.5
SECTYPE,2,BEAM,RECT
SECDATE,0.6,0.4
secoffset,user,0.3,0
MP,NUXY,1,0.2
MP,DENS,1,3000
mp,ex,1,32680e6
MP,NUXY,2,0.2
MP,DENS,2,3000
mp,ex,2,32680e6
r,2,0.2,0.2,0.2,0.2k,1
k,2,5
k,3,5,4
k,4,0,4
l,1,4
l,4,3
l,3,2
l,1,2lsel,s,line,,2
latt,1,,1,,,,2
lesize,2,1allsel,all
lsel,s,line,,1
latt,1,,1,,,,1
lesize,1,1allsel,all
lsel,s,line,,3
lesize,3,1
latt,1,,1,,,,1
allsel,all
lmesh,1,3,1/eshape,1
al,all
asel,s,area,,1
aatt,2,2,2
lesize,4,1
amesh,1
d,1,all
d,15,all
d,16,all
d,17,all
d,18,all
d,11,all/solu
d,6,ux,0.1
/post1
pldisp,1