How can I check internet connection in LAN environment through proxy? I use code

#DEFINE FLAG_ICC_FORCE_CONNECTION 1
DECLARE Long InternetCheckConnection IN Wininet.dll String Url, Long dwFlags, Long Reserved

lcUrl = "http://www.google.com"
IF InternetCheckConnection(lcUrl, FLAG_ICC_FORCE_CONNECTION, 0) != 0
? "Connection is available"
ELSE
? "No Connection"
ENDIF

and it allways returns "no connection" on PC with proxy. On PC without proxy everything works fine.

Thanks in advance.