Error validating a inputbox with regular expressions

Dear experts:

Hope you are having a great week!

I'm having a hard time validating the information provided on an inputbox, it must be an email from the outlook domain. This is the code I'm using to evaluate the email provided (ROemail)

        ROemail = Application.InputBox("Please enter your email to receive notifications about the status of this format.", Title:="Risk owner Email address", Default:="email@outlook.com", Type:=2)
            If StrPtr(ROemail) = 0 Then
                MsgBox ("Action cancelled by user. QA not requested!")
                Exit Sub
            ElseIf ROemail = vbNullString Then
                MsgBox ("No email entered. Please provide a valid email")
            Else
                If ValidateEmailAddress(ROemail) = False Then
                        MsgBox ("The information provided is not a valid email from the Outlook domain, please verify.")
                Else
		        'DO STUFF
                End If
	    End If

The Function ValidateEmailAddress() that validates the String goes like this:

Public Function ValidateEmailAddress(ByVal ROemail As String) As Boolean
    On Error GoTo Catch
    
    Dim objRegExp As Object
    Dim blnIsValidEmail As Boolean
    
    objRegExp.IgnoreCase = True
    objRegExp.Global = True
    objRegExp.Pattern = "^(([\w\d\-\_\.])+@outlook\.com,*\s*)+$"
    
    blnIsValidEmail = objRegExp.Test(ROemail)
    ValidateEmailAddress = blnIsValidEmail
      
    Exit Function
    
Catch:
    ValidateEmailAddress = False
End Function

But for some reason it's not working and it's sending me this errors related to the objRegExp, It's the first time using a function and a Regular Expression so I'm not sure if I'm doing something wrong or something is missing.

Could you please advice me?

Thank you so much in advance!