No getter setter found for property, binding problem?

I am new to Spring Roo and I searched the forums for an answer but I cant find it.

What i want to do is very simple.

I have an class Person like this.

class Person
string firstname
string lastname
Address address;

class Address
string street
int houseNumber

When Roo is generating my JSP there is something like 2 textfields (firstname and lastname) and a combobox named Address. So my ModelAttribute="Person"

<field:input field="firstname " ...
<field:input field="lastname" ...
<field:select field="address" ...

What I want, is not a combox to select the right address but just simple text field for street and housenumber. So i thought I put and new text field on the same page like this <field:input field="address.street" ...

I thought this must work. But when i want to open my page (just an get request). In the log i see the message 'coudn't found getter and setter for property address.street.

I guess its very simple but I can't find a solution. Can someone help me ?

Thanks.