INSERT INTO problem

Hello all,
I'm trying to do an INSERT INTO using a UNION of two selects.  I 
received an error:
  "ERROR:  Unable to convert varchar to int2 for column isdepartment"

I started simplifying the INSERT INTO to help me get to the root cause.  
I removed the UNION and continued simplifying.

I eventually ended up with this line that still gives me the error:
insert into reportentity
   select 'D0'||text(departmentid) as reportentityid,
   departmentname as reportentityname,
   '1'::int2 as isdepartment,
   departmentdescription as reportentitydescription,
   departmentsummary as reportentitysummary
from department where isreportentity > 0;

Now removing the last two fields lets the INSERT INTO run without errors:
insert into reportentity
   select 'D0'||text(departmentid) as reportentityid,
   departmentname as reportentityname,
    '1'::int2 as isdepartment
from department where isreportentity > 0;

Some of the description and summary fields do have null values; is that 
causing the error?   (I'm not sure why it would but that's all I can 
think of)

Oh here's the format of the reportentity table:
reportentityid char(5) not null     
reportentityname varchar(110) not null   
reportentitydescription  varchar(4000) 
reportentitysummary varchar(4000)                       
isdepartment  int2

any help would be appreciated.

Tom Jenkins
devIS - Development Infostructure
http://www.devis.com