APi and Geocode the right query


i’d like to use api to get usernames of people that tweetted in a specifici geocode location(radius 200 m) and using an hashtag but when i write a c# code and my query is like:

%23nicetolinkyou%26geocode=41.82268,12.49623,0.2km OR %23nicetolinkyou&geocode=41.82268,12.49623,0.2km
I receive a 401 bad autorizathion

if i use only %23nicetolinkyou it works

What’s the right query (right special chars, i suppose) to get this result please?
Thank you in advance for your help