Script Monitors creating bad alerts

In my monitoring system i m using mostly script monitoring. But problem is that it is creating a lot of false alarm . False alarm of monitor is coming because of failing to fetch the values from the server. In the attribute value "No data available" comes. Most of the time when i checked the monitored server during that it was working fine i dont understant why monitoring polling engine failed to fetch the values from the servers.
I have added the dependency thing and increased the number of polls before changing the health/availabilty sate from up to down but still .. false alarm are there all the time.
Any tip or solution related to this.
Regards
Farooq