c# - Tweetsharp HTTP 403 -

i have problem logging on twitter using asp.net 4 c# , twitterizer. first create twitterservice object

twitterservice service = new twitterservice(key , secret); 

then request token:

oauthrequesttoken requesttoken = service.getrequesttoken(                     "http://127.0.0.1:16608/callbackhandlers/twittercallback.ashx"); 

then uri:

uri uri = service.getauthorizationuri(requesttoken); 

and redirect:

httpcontext.current.response.redirect(uri.tostring()); 

my app redirected twitter. when enter user id , password http 403 error. if press button on browser twitter no longer asking me enter userid , pwd instead there , authorize button. when press authorize button, twitter redirects site , proceeds expected.

i cannot seem enter userid , pwd without getting 403 error. when error browser address showing:-

https://api.twitter.com/oauth/authorize

please note callback url twitter app setup same 1 in getrequesttoken call above.

it appears if twitter not know go next!!!.

any assistance welcomed.

robert.