这样算之后显示：结构体内容引用自非结构体数组对象。请问是哪里出现问题了吗？

clear;clc
path1 = 'D:\172306\work\data';
subdir1 = dir(path1);
FileNames1 = sort_nat({subdir1.name});
FileNames1 = FileNames1(3:32);

f=strcat(path1,FileNames1{1});
subdir2 = dir(f);
FileNames2 = sort_nat({subdir2.name});
FileNames2 = FileNames2(3:202);

savepath='E:\matlab\1lunshiyan';

for j=1:30% FileNames1中总数为30
for k=1:50% FileNames2中总数为50

I1_Trace = strcat(path1, FileNames1(j),'\',FileNames2(1+50-k));
I2_Trace = strcat(path1, FileNames1(j),'\',FileNames2(1+100-k));
U1_Trace = strcat(path1, FileNames1(j),'\',FileNames2(1+150-k));
U2_Trace = strcat(path1, FileNames1(j),'\',FileNames2(1+200-k));
%读数据并拼接
I1=load(I1_Trace{1});
I2=load(I2_Trace{1});
U1=load(U1_Trace{1});
U2=load(U2_Trace{1});
Data=[I1.Iabc1.time, U1.Vabc1.data, U2.Vabc2.data, I1.Iabc1.data, I2.Iabc2.data];
j1=15+j*5;
R1=50+k*5;

savepath1=strcat(savepath,'1',num2str(j1),'2',num2str(R1),'.txt');%文件保存位置
dlmwrite(savepath1,Data);%写文件

end
end

运行结果及报错内容

显示Data=[I1.Iabc1.time, U1.Vabc1.data, U2.Vabc2.data, I1.Iabc1.data, I2.Iabc2.data];这一行是结构体内容引用非结构体数组对象