You are not doing it right you are asking AMS to check for a string your not checking the string is it includes something you asking ams to check the full string.
SID = Label.GetText("label1");
sKey = Label.GetText("Label2");
result = HTTP.Submit("http://siteadim.com/altklasor/zaman.php", {sKeyGo=sKey,IdGo=SID}, SUBMITWEB_POST, 20, 80, nil, nil);
if String.Find(result, "Bas-Tarihi : ") ~= -1) then
result = String.Replace(result, "Bas-Tarihi : ", "", false);
Label.SetText("Label5", result);
end
Also update your php mysql is no longer a vailed means to code, use PDO or mysqli
Sorry English