crosstab help

I have a simple table
item_number  week_of               planned_qoh
------------------  ------------------       ------------------
00005            2012-02-05           30
00005            2012-02-12           40
00005            2012-02-19           50


where 
item_number text
week_of date
planned_qoh integer

I have a function that returns the table as above:

chromasun._chromasun_totals(now()::date)

I want to see

00005   2012-02-05   2012-02-12    2012-02-19                   30                  40                 50

This is what I have tried (although, I have tired many others)

select * from crosstab('select item_number::text as row_name, 
to_char(week_of,''MM-DD-YY'') as bucket, planned_qoh::integer as buckvalue 
from xchromasun._chromasun_totals(now()::date)')
as ct(item_number text, week_of date,  planned_qoh integer)

I get 
ERROR:  return and sql tuple descriptions are incompatible

What am I doing wrong?

Johnf