0 ms Response Time and device discovery success rate

1) I am using the older version 6.0.2 (free) and the newest version 7.2.8 (trial), both 32 bit, Windows 7, for testing.
I found that the Response Time values in the scan results in the older version are all 0 ms; and in the latest version the values range from 0 to 2000 ms. That is always similar if scan is repeated. Does this mean that the older version is faulty?

2) What is the reason that sometimes a network address was found or not (for up to 10 items, within the free trial limitations)? I have increased ping to 2000 ms but that doesn't help.

1) Version 6.0.2 shows zero response time when the device was discovered via an ARP request (arping) rather than ICMP request (regular ping). The latest version measures this time, whereas the older version simply reports a zero. Longer response times are typical of mobile devices that are generally found in sleep mode.

2) Likewise, some devices may be in a sleep state, causing them to respond late or not respond at all. To improve discoverability, you could set the timeout to 3000-4000 ms and set the number of attempts to 3 or so. The downside of this is that the scan will take longer.