Match validator not working in Yii 1.1

I need to validate that a customer is using a valid subdomain name as well as making sure some other required fields are present. I have created the following rule in my model class:

public function rules()
        return array(
            array(',c_customerSubdomain, c_custAdminUser,c_adminPassword,c_adminContact', 'required', 'message' => "{attribute} is TEST required."),
            array('c_customerSubdomain', 'match', 'pattern' => '/^[a-z0-9_]*$/', 'message' => "Customer Subdomain should contain only alphanumeric and underscore.", "allowEmpty" => false),

I am testing whether or not the rule is firing by changing the message for required values to: {attribute} is TEST required.

When I submit the form with all of the field blank, the result is as expected.

However, when I populate the field for subdomain with an illegal value, such as “ASD# a”, I am expecting to get a validation error. However, instead, the rules bypass all of the other validation errors and attempt to save the model.

Did you try the same pattern on Regex editor online or offline that supports PHP? or with PHP regex functions?

I have not used Yii1 for many years but I will start by looking in Match validator code and see how it does it. May be there you can discover something!