DBX no conecta

[Paulao]

Mi aplicacion trabaja con dos bancos de datos: MySql y SqlServer 2008. El SqlServer funciona bien, pero con MySql no. Abajo mi archivo INI de conecion:

Código Delphi [-]
if banco = 'MySql' then
  begin
    SqlConnection1.ConnectionName                        := 'MySQLConnection50';
    SqlConnection1.DriverName                            := 'MySQL50';
    SqlConnection1.GetDriverFunc                         := 'getSQLDriverMYSQL50';
    SqlConnection1.LibraryName                           := 'dbxopenmysql50.dll';
    SqlConnection1.LoginPrompt                           := False;
    SqlConnection1.VendorLib                             := 'libmysql.dll';
    SqlConnection1.Params.Values['DriverName']           := arq_conexao.ReadString('MySql','DriverName','');
    SqlConnection1.Params.Values['HostName']             := arq_conexao.ReadString('MySql','HostName','');
    SqlConnection1.Params.Values['DataBase']             := arq_conexao.ReadString('MySql','DataBase','');
    SqlConnection1.Params.Values['User_Name']            := arq_conexao.ReadString('MySql','User_Name','');
    SqlConnection1.Params.Values['Password']             := arq_conexao.ReadString('MySql','password','');
    SqlConnection1.Params.Values['BlobSize']             :=  arq_conexao.ReadString('MySql','BlobSize','');
    SqlConnection1.Params.Values['LocaleCode']           :=  arq_conexao.ReadString('MySql','LocaleCode','');
    SqlConnection1.Params.Values['ErrorResourceFile']    :=  arq_conexao.ReadString('MySql','ErrorResourceFile','');

  end
  else
  if banco = 'SqlServer' then
  begin
    SqlConnection1.ConnectionName                        := 'MSSQLConnection';
    SqlConnection1.DriverName                            := 'MSSQL';
    SqlConnection1.GetDriverFunc                         := 'getSQLDriverMSSQL';
    SqlConnection1.LibraryName                           := 'dbexpmss.dll';
    SqlConnection1.LoginPrompt                           := False;
    SqlConnection1.VendorLib                             := 'OleDb';
    SqlConnection1.Params.Values['DriverName']           := arq_conexao.ReadString('SqlServer','DriverName','');
    SqlConnection1.Params.Values['HostName']             := arq_conexao.ReadString('SqlServer','HostName','');
    SqlConnection1.Params.Values['DataBase']             := arq_conexao.ReadString('SqlServer','DataBase','');
    SqlConnection1.Params.Values['User_Name']            := arq_conexao.ReadString('SqlServer','User_Name','');
    SqlConnection1.Params.Values['Password']             := arq_conexao.ReadString('SqlServer','password','');
    SqlConnection1.Params.Values['BlobSize']             :=  arq_conexao.ReadString('SqlServer','BlobSize','');
    SqlConnection1.Params.Values['LocaleCode']           :=  arq_conexao.ReadString('SqlServer','LocaleCode','');
    SqlConnection1.Params.Values['ErrorResourceFile']    :=  arq_conexao.ReadString('SqlServer','ErrorResourceFile','');
    SqlConnection1.Params.Values['MSSQL TransIsolation'] :=  arq_conexao.ReadString('SqlServer','MSSQL TransIsolation','');
    SqlConnection1.Params.Values['OS Authentication']    :=  arq_conexao.ReadString('SqlServer','OS Authentication','');
  end;

El error es un AccessViolation en dbxopenmysql50.dll, pero si hago la conecion directa en el componente SqlConnection, con los mismos parametros yo consigo conectar al banco.