I getting the follwing mapping error:

<net.sf.hibernate.MappingException: Problem trying to set property type by reflection>net.sf.hibernate.MappingException: Problem trying to set property type by reflection

I believe this is the part thats causing the error

<id name="forecastID" type="long" unsaved-value="null" >
<column name="FC_DS_ID" sql-type="BIGINT" not-null="true"/>
<generator class="assigned"/>
</id>

The above is an autonumber field in the table, the field type is a BIGINT.
The database is DB2

What is the actual java type of id ?
Do you have setter and getter ?

it was a problem with setter
working fine now