Regular match is not valid

Today in the background of the project to do regular matching extraction operation, how can not be taken to the value, the specific regular expression and the proposed string as follows:

The regular expression above is correct, but the result of the match is to extract the whole content, which is not the result I want. To the standard regular expression, continue testing as follows:

The test is no result, it doesn't work. No, I had to ask the master: regular expression is not recognized

Modify the regular expression as follows to continue the test

Successfully presented values

Summary: Before writing the regular expression also has not added around two parentheses, can also be matched successfully, I do not know why, this time is not. No rules inadequate surrounding area, the future is honest according to the rules of the son.

Regular match is not valid