You need to check your data. It may have entry errors. Or, two of your variables have the same values. I had the same problem, and later found that I made a mistake in data entry.

two of your variables have the same values
难道这不许吗？

十分感谢楼上的指点 我马上去看看

现在是这个问题，谁帮忙解答一下啊？