ANSYS进行移动荷载出现时间错误

Present time 1.E-06 is less than or equal to the previous time in a     
transient analysis.
在进行循环求解时，出现这种问题是怎么回事呀
以下是我的求解命令流
/prep7
csys,0
L=32.4              
                
v=72*1e3/3600      
                
gra=9.8
nstart=node(6.35,1.8,0)  
nsel,s,loc,x,6.35
nsel,r,loc,y,1.8
*get,nt,node,,count
*dim,pno,,nt
pno(1)=node(6.35,1.8,0)
*do,i,2,nt
pno(i)=nnear(pno(i-1))
nsel,u,,,pno(i-1)
*enddo
nsel,all
finish
/solu
antype,trans
outres,all,all
autots,on
nsubst,1
betad,0.01
timint,on
*do,i,1,nt
ti=(nx(pno(i))-nx(pno(1)))/v
*if,ti,le,1.00e-10,then
ti=1.00e-6
*endif
time,1.00e-06
fdele,all,all
f,pno(i),fy,-p
solve
*enddo