ROO web mvc conversion error

[enorrmann]

I created an entity, "Tasa" with a BigDecimal field.
When I try to save a new "Tasa", with some decimal value like 12.30, the server says that "The request sent by the client was syntactically incorrect ()."
Looking at the log I found:

Failed to convert from type java.lang.String to type java.lang.Long for value '12.30';

How do I force spring to convert to BigDecimal instead of Long ?
Regards
Emilio