Error data types do not match

I have a flatfile source with qty,title and author..i add a lookup and in that i establish relation between title and titel of pubs database..but i am getting an error..
one or more columns do not hav supported data types,or their datatypes do not match..i checked both hav dt_str,and in database pubs title is varchr..so why this eror?I think the error is quite clear. Open your lookup and navigate to the olumns tab. Now hover over each column you wish to join on the left and right hand sides. The tooltip will give you the SSIS types concerned. Do they match? If not what are they and why do you think they should? If they do not match use the Data Conversion or Derived Column transforms to convert as required.|||hi daaren,
they do match..both dt_str..why still error?
thks|||

Check the error rmessage carefully, maybe it is not the lookup component which is raising the error, or is this in the Lookup UI, in which case it obviously is?

Are the lengths and code pages appropiate?

Failing that post some sample data from the file, the buffer types used on the file output path, and the DDL for the lookup table and I'll try and reproduce to see the issue.