Error ORA-01460 warning ORA-01461 during running a mapping with parameters

Question

Oracle 10g release2(10.2.0.1.0), OWB 10.2.0.1.31, Workflow server 2.6.4
I have a simple process flow ( start -> mapping -> end).
The mapping consists of 4 input groups(3 ordinary tables<INGRP1, INGRP2, INGRP3> and 1 mapping input parameter operator <INGRP4>), a joiner, a filter, an expression operator and 1 output group.
I want to use two variables in join condition, so I bound two mapping input parameters(<INGRP4.SRC_SYS_CDE> and <INGRP4.ADMIN_ORG_NUM>) with two parameters of the process flow's start activity.
Those two mapping input parameters are of type char, one is 4-char long and the other is 2-char long. So I set both of the two parameters of the start activity as String, one as 08, another as 7504.
My join condition is:
INGRP1.ORGIDT = INGRP2.SOURCEORGANIZATIONNO AND
INGRP2.SOURCESYSTEMCODE = INGRP4.SRC_SYS_CDE AND
INGRP2.ADMINORGANIZATIONNO = INGRP4.ADMIN_ORG_NUM AND
INGRP1.CURCDE = INGRP3.NUM(+)
There are no errors and warnings in validation, generation and deployment process, but when I run the process flow, it always finishes blankly(zero insert) with no error and warning messages. It should insert more than 20,000 rows.
When I run the mapping and set the parameters 08 and 7504 at the parameter prompt, then start, the following error and warning occurs.
Error ORA-01460: unimplemented or unreasonable conversion requested
Warning ORA-01461: can bind a LONG value only for insert into a LONG column
So what's the problem? How can I fix it?

Answer 1

The problem was mapping input parameter type.
VARCHAR2-type mapping input parameter works with String-type PF parameter. But CHAR-type won't.