我在进行主成分分析时将分析因素拖入Analyse-Data Reduction-Factor-Varibles，但发现只能拖入17个因素，超过以后就会出现

Warnings
SPSS read a line of syntax which contains one or more characters which are invalid in the current locale.  These characters have been converted to question marks.
Text: J18工作
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.

请问什么原因？如何继续？