onCheckPropertyValues with Name/CN during Create Object

Is it possible to check on Name/CN during a User creation

Problem is that we define prefix rules

xxx_abc_ (for default value genaration in web interface, prefix must be prefiled if form is clicked)

xxx_abc_{*}

this logic allows the user to click next without supplying text after the prefix. (He can send value xxx_abc_ )

I would like to fix this by checking if there are characters after _abc_

In the debug log i see that SetPolicyComplianceInfo is triggered but i'm not stoped from creating the user

function onCheckPropertyValues($Request) {
	######### Control #########
	# Form name to match the value from the request
	$Formname = "NewDeviceUser"

	# Exit function if request is not for a user
	if ($Request.Class -ne 'user') { return }

	# Catch GetInControl NULL
	try {
		$Form = $Request.GetInControl("Form")
	}
	catch {
		return
	}

	# Check if the form name from the request matches the one defined above
	if ($Form -eq $Formname) {
		######### Controlled Attributes #########
		$attCn = "cn"

		######### Get Request #########
		$cn = $Request.Get($attCn)

		######### Policy #########
		# Regex pattern: variable part, followed by '_dvc_', and at least one character after that
		if ($cn -match '.+_dvc_.+') { return }
		else {
			$Request.SetPolicyComplianceInfo($attCn, $constants.EDS_POLICY_COMPLIANCE_ERROR, "Invalid: No characters found after '_dvc_'.")
		}
	}
}

DEBUG:     ! SET $cn = 'TEST_DVC_'.
DEBUG:  278+ 		if ( >>>> $cn -match '.+_dvc_.+') {}

DEBUG:  280+ 			 >>>> $Request.SetPolicyComplianceInfo($attCn, $constants.EDS_POLICY_COMPLIANCE_ERROR, "Invalid: No characters found after '_dvc_'.")

 Call method '$Request.SetPolicyComplianceInfo'
     Arguments list:
         [1] : Value=cn : Type=System.String
         [2] : Value=1 : Type=System.Int32
         [3] : Value=Invalid: No characters found after '_dvc_'. : Type=System.String
         [4] : Value=False : Type=System.Boolean
  Call '$Request.get_PolicyComplianceInformation'
DEBUG:  283+  >>>>