Banxico Currency Rate Update error

[joseponzo]

hi
everything works except banxico. does not work since it was installed. openerp 7, currency rate update 7.0.0.7
2014-07-09 13:58:42 ERROR : 'NoneType' object is not iterable
2014-07-08 17:26:32 ERROR : 'NoneType' object is not iterable
2014-07-08 14:53:15 ERROR : 'NoneType' object is not iterable
no more information in the openerp log or apache log
may change the xml format of the bank (banxico)
look like this:
<cb:exchangeRate>
<cb:value frequency="daily" decimals="4">12.9949</cb:value>
<cb:baseCurrency>USD</cb:baseCurrency>
<cb:targetCurrency>MXN</cb:targetCurrency>
<cb:rateName>ParaPagos</cb:rateName>
</cb:exchangeRate>
regards