Sometimes VitalSigns is unable to gather statistics about Domino servers. In the log files you see a variation of the error message "serverstats.dll not found". There are two possible causes:
1) The Visual C++ runtime is not installed
2) The path variable on the monitoring station is not pointing to the location of the Notes client.
Check the path very carefully. We have seen cases where the path was correct at one time and later the Notes client was moved. For example the path could point to c:\program files(x86)\IBM\notes folder but the correct location is c:\program files(x86)\IBM\lotus\notes