invoke web service issue "Failed to connect to host"

Hello sir/madam

      I tried to invoke web service,many of clients work fine,however a few of them ocurred issue which is  Failed to connect to host xxx.xxx.xx.xx port xxx no error,it's weird that I could open the web page of web serive in browser which it means that netowrk is fine to client to the server.What I have done wrong,here is my code:

soapconnection lsc_conn

n_member_serversoap myy_ws

string str_endpoint_1

str_endpoint_1 = trim(gs_endpoint)

lsc_conn=create soapconnection

lsc_conn.createinstance(myy_ws,'n_member_serversoap',str_endpoint_1)

lsc_conn.settimeout(45)//this is code which I added lately,because I thought it's a timeout problem and tried to resolve this issue by //setttimeout,however,It doesn't help,the issue didn't vanish.

try

ls_re=myy_ws.uf_retrieve(as_syntax,as_sql,as_returnerr,ls_dwo_blob)

catch(soapexception e)

messagebox("error:","soap exception:"+e.getmessage())

li_re="soap exception"+e.getmessage()

catch (PBXRuntimeError e2) 

MessageBox("PBXrumtime erro",e2.getmessage())

catch (RuntimeError e3) 

MessageBox("PB runtime error", e3.getmessage())

end try

any idea?I have serached Google and I don't have found any valuable results.

regards

Ken