pipe doesn't work when --ackmate is chosen

[WaveLong]

I want to use ag in my code: step 1. write text content into a pipe, and then assign this pipe to ag shell task's standard input step2. run shell step3. read match result from an output pipe but when I use "--ackmate", the input pipe doesn't work eg:

text: info aaaainfossss info there is a info too

cat testlog.txt |ag "info", OK cat testlog.txt |ag "info" --ackmate, not OK

How to fix it?