doesn't send the value to insert statement

[Karthikeyan Pandurangan]

Hi,
     I am stuck with the problem in <selectKey> & insert statement usage.

My insert statement.

<insert id="insertDonorInfo">
       <selectKey resultClass="java.lang.String" >
         SELECT to_char(FN_GETDONORID) AS "strDonorID" FROM DUAL
       </selectKey>
        INSERT INTO DONOR (
        DONOR_ID,
        CATEGORY,
         CREATED_BY,
         DATE_CREATED
        )
        VALUES (
        #strDonorID:VARCHAR#,
        #strCategory#,
         #strCreatedBy#,
        sysdate
        )
    </insert>

I am getting the follow exception from DB

com.ibatis.common.jdbc.exception.NestedSQLException:
--- The error occurred while applying a parameter map.
--- Check the insertDonorInfo-InlineParameterMap.
--- Check the statement (update failed).
--- Cause: java.sql.SQLException: ORA-01400: cannot insert NULL into ("xxxx"."D
ONOR"."DONOR_ID")

The ibatis log for statements

{pstm-100010} PreparedStatement:           SELECT
to_char(FN_GETDONORID) AS "strDonorID" FROM DUAL
{pstm-100010} Parameters: []
{pstm-100010} Types: []
{rset-100011} ResultSet
{rset-100011} Header: [strDonorID]
{rset-100011} Result: [200500000005]
{pstm-100012} PreparedStatement:                  INSERT INTO DONOR (
DONOR_ID,    CATEGORY, CREATED_BY         , DATE_CREATED         )    
    VALUES (         ?,         ?       ,?         ,sysdate         )
{pstm-100012} Parameters: [, I,  ADMIN]
{pstm-100012} Types: [java.lang.String, java.lang.String, java.lang.String]
Returned connection 20980795 to pool.
com.ibatis.common.jdbc.exception.NestedSQLException:
--- The error occurred while applying a parameter map.
--- Check the insertDonorInfo-InlineParameterMap.
--- Check the statement (update failed).
--- Cause: java.sql.SQLException: ORA-01400: cannot insert NULL into ("XXXX"."D
ONOR"."DONOR_ID")

Please help me to solve it. Thanks in advance.

Regards
p.karthi