POST to /statuses/update.json with special characters fails error code 32: Could not authenticate you


Hi All
I have successfully integrated Twitter Post tweets functionality with my classic ASP application. I did find though that it had issues with special characters like :, (, * - , . etc. Some of these need to be replaced by their Hex codes and some of them not e.g. (. - _ ~).
Well having taken care of most of the special characters I am now fumbled with internationalization. To start with I am using Spanish characters like Á É Í Ñ Ó Ú etc there are so many of them. I did customize code to produce exactly the same base string as Twitter OAuth tool would generate but everytime I get this error 32 : Could not authenticate user.
Has anybody done similar stuff? Any ideas?

For a test data = status=X€X¡X«X»X¿XÁXÉXÍXÑXÓXÚXÜXáXéXíXñXóXúXûXüXýXþXÿX

OAuth Tool generated Base String


And my script generated


as you can see it is same other than few paramters which ofcourse will change for each request. I can find out what is happening, please help.