LayaUISample.max.js:321 Uncaught TypeError: Cannot set property 'text' of null

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var txt:Label = cell.getChildByName("listNumber") as Label;
txt.text = data.listNumber;
调试时会报：LayaUISample.max.js:321 Uncaught TypeError: Cannot set property 'text' of null
引擎版本 LayaAirAS3_1.7.7_beta

cuixueying

最好有个例子，我们看下什么问题，谢谢！