Calling Mysql SP from ASP creates error

When I tried calling a MySql stored proc from classic ASP, I get this error:

OUT or INOUT argument 5 for routine spAddContactUsEmail is not a variable or NEW pseudo-variable in BEFORE trigger

Here is the SP (which I can call successfully from Mysql workbench):

CREATE DEFINER=`root`@`localhost` PROCEDURE `spAddContactUsEmail`(
    In vcName varchar(50),
    In vcPhone varchar(50),
    In vcEmail varchar(50),
    In txtComments text,
    Out intNewID int
)
BEGIN
    Insert Into contact_us (`Name`, Phone, Email, Comments, DateCreated) 
    Values (vcName, vcPhone, vcEmail, txtComments, now());
    Set intNewID = Last_Insert_ID();
END

Here is the ASP code:

Dim con
Dim cmd
Set con = Server.CreateObject("ADODB.Connection")
con.Open "connection string" 
Set cmd = Server.CreateObject("ADODB.Command")
cmd.ActiveConnection = con
cmd.CommandType = adCmdStoredProc
cmd.CommandText = "spAddContactUsEmail"
cmd.Parameters.Append cmd.CreateParameter("vcName", adVarChar, adParamInput, 50, "John Doe")
cmd.Parameters.Append cmd.CreateParameter("vcPhone", adVarChar, adParamInput, 50, "333-4444")
cmd.Parameters.Append cmd.CreateParameter("vcEmail", adVarChar, adParamInput, 50, "test@yahoo.com")
cmd.Parameters.Append cmd.CreateParameter("txtComments", adLongVarChar, adParamInput, Len("hey"), "hey")
cmd.Parameters.Append cmd.CreateParameter("intNewID", adInteger, adParamReturnValue)
cmd.Execute

The error occurs on the cmd.Execute line. Thanks in advance.