Flex - 按文本输入搜索/过滤DataGrid

I’m using a filter setup that I found online and I’m having trouble filtering my mx:DataGrid using three components – comboBox, checkbox and text input. The checkbox and comboBox are working properly with my IFilter interface and Filter class, but I’m unable to get the search input working correctly. Here’s of the code from the source filesI’m using a filter setup that I found online an