matlab解方程得到空集结果，而已经有大佬可以解出数值解，不知道我代码哪里写错了。

Question

代码如下：

方程如下：

syms R H B L Z theta theta1 theta2 a3 a4 yuxian1 yuxian2 zhengxian1 zhengxian2 xcf ycf zcf xdf ydf zdf xof yof zof
H=60;B=110;R=4000;L=280;xof=4060;yof=110;zof=1000;z=1000;theta=0.53;

f1=xcf-( (cos(theta1)*cos(theta2))*(-H)+(-sin(theta2))*(B+a3)+(cos(theta2)*sin(theta1))*(-140)+(R+H) );

f2=ycf-( (cos(theta1)*sin(theta2))*(-H)+ cos(theta2)*(B+a3)+sin(theta1)*sin(theta2)*(-L/2)+B );

f3=zcf-( (-sin(theta1))*(-H)+(cos(theta1))*(-L/2)+1000 );

f4=xdf-( (cos(theta1)*cos(theta2))*(-H)+(-sin(theta2))*(B+a4)+(cos(theta2)*sin(theta1))*(L/2)+(H +R) );

f5=ydf-( (cos(theta1)*sin(theta2))*(-H)+(cos(theta2))*(B+a4)+(sin(theta1)*sin(theta2))*(L/2)+(B ) );

f6=zdf-( (-sin(theta1))*(-H)+(cos(theta1) )*(L/2)+(Z - L/2 ) );

f7=(xcf-xof)^2+(ycf-yof)^2+(zcf-zof)^2-H^2-(L/2)^2-(B+a3)^2;

f8=(xdf-xof)^2+(ydf-yof)^2+(zdf-zof)^2-H^2-(L/2)^2-(B+a4)^2;

f9=xcf^2+ycf^2-R^2;

f10=xdf^2+ydf^2-R^2;

f11=yuxian1-cos(theta1);

f12=yuxian2-cos(theta2);

f13=zhengxian1-sin(theta1);

f14=zhengxian2-sin(theta2);

[yuxian1,yuxian2,zhengxian1,zhengxian2]=vpasolve(f1,f2,f3,f4,f5,f6,f7,f8,f9,f10,f11,f12,f13,f14,yuxian1,yuxian2,zhengxian1,zhengxian2)

按回车得到的是空集结果：
yuxian1 =

Empty sym: 0-by-1

yuxian2 =

Empty sym: 0-by-1

zhengxian1 =

Empty sym: 0-by-1

zhengxian2 =

Empty sym: 0-by-1

有位大佬得到的结果是：
theta1 1.49817430053185
theta2 0.386614141688036
a3 -299.773626223014
a4 612.32802093724
yuxian1 0.0725582088327057
yuxian2 0.926191019912681
zhengxian1 0.997364179390352
zhengxian2 0.37705463083366
xcf 3998.19789437623
ycf -120.056642488088
zcf 1049.68370152684
xdf 3912.93567355294
ydf 830.020731449993
zdf 930

为啥我的方程按回车就是空集解呢。。？