我是SPSS的初学者，我不明白为什么我在做分析的时候会出现一个对话框，我很难解决这个问题，请哪位高手可以帮我讲解一下，谢谢，不胜感激。。。
就是在做主成分分析时候会显现如下：
Warnings
Text: 总资产报酬率ROA
An undefined variable name, or a scratch or system variable was specified in a variable list which accepts only standard variables.  Check spelling and verify the existence of this variable.
This command not executed.


Warnings
Text: 总资产报酬率ROA报告期去年
An undefined variable name, or a scratch or system variable was specified in a variable list which accepts only standard variables.  Check spelling and verify the existence of this variable.
This command not executed.

请问出现的原因是什么？
谢谢