I am learning the basics of rest api integration.
I am using two sfdc developer orgnzs. flipkart(is the source) and hdfc(is the destination).

I am calling a webservice defined in destination from source to check if an account name already exists.

I am using OAUTH2.0 authentication and I have access token generated.

code in destination side.

code in destination side
===================
@RestResource(UrlMapping='/RestMapping1/*')
global class RestObject
{
@HTTPGet
   webservice static void SearchByAccountName()
   {
     String account_name=RestContext.request.params.get('accName');
     
     system.debug('account Name found in destination = '+account_Name);
     
   }
}

code in source side
==============
Public PageReference SearchByAccountName()
       {
         if (accesstoken != NULL)
         {
       
           HTTP h = new HTTP();
     
           HTTPRequest req = new HTTPrequest();
     
           req.setMethod('GET');
     
           req.setHeader('Authorization','Bearer '+accesstoken);
       
           req.setHeader('Content-Type','application/json; charset=UTF-8');
       
           req.setHeader('Accept','application/json');
       
           acc=[select Name from Account where Name LIKE '%Sunshine%' LIMIT 1];
           
           req.setEndpoint('https://ap2.salesforce.com/services/apexrest/RestMapping1?accName='+acc.Name);
           
           HTTPResponse resp;
           try
           {
             resp=h.send(req);
             string json=resp.getBody();
             system.debug('json = '+json);
            
           }
       
           catch(system.CallOutException ex)
           {
           
           }

when I check debug logs I am getting statuscode=400 (bad request).
Can any one tell me where is the issue and how to resolve it?

smita