ASIHTTPRequestErrorDomain Code=5 - unable to create request

Hi all,

I'm using iOS echoprint sample, but stuck in this part:

NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://%@/api/v4/song/identify?api_key=%@&version=4.11&code=%s", API_HOST, API_KEY, fpCode]]; ASIHTTPRequest * request = [ASIHTTPRequest requestWithURL:url];

it generates error ASIHTTPRequestErrorDomain Code=5 - unable to create request

fpCode is const char generate with the codegen.

Please help... Thanks in advance.