HMT140 works best with signal strengths above -63 dBm (for 802.11b mode) and -75 dBm (for 802.11g mode). If the signal strength is less, HMT140 may work marginally or not at all. Stronger signal strength improves transmission performance.
Since the signal strength will vary from sample to sample, you should take multiple samples to determine the signal strength. View signal strength on the Status tab and in the Available Networks window (click the Find Networks button on the Setup tab).