I have tried enabling receiving billing addresses with PayPal sandbox by adding the following option:
REQBILLINGADDRESS=1 (documented here: https://www.paypalobjects.com/webstatic/en_US/developer/docs/pdf/pfp_expresscheckout_pp.pdf)
For the call to SetExpressCheckout.
However, I receive the following error:
'ACK': 'Failure',
'BUILD': '6675672',
'CORRELATIONID': '4d9afd327754a',
'L_ERRORCODE0': '11601',
'L_LONGMESSAGE0': 'Billing address request is not enabled for merchant',
'L_SEVERITYCODE0': 'Error',
'L_SHORTMESSAGE0': 'Request for billing address failed',
'TIMESTAMP': '2013-06-28T16:32:22Z',
'VERSION': '72.0'
I know receiving billing addresses is possible as the Humble Bundle do it here:
How do I change my sandbox account to enable billing address requests? and what do I need to do in order to enable this for a live account?
Along with passing over the variable in your code, you also need to have the feature enabled on your account. For your live account you will need to contact PayPal Bussiness/Customer support and request this to be enabled on your account. I have enabled it on your sandbox account, you should now be able to test with it.