Problem invoking WLST - java.lang.RuntimeException: Could not find the OffLine WLST class

When instlling Webserver on Tools 8.51 and Applicaion 9.1, the PIA  failed to configure by saying,

Problem invoking WLST - java.lang.RuntimeException: Could not find the OffLine WLST class 

I googled for the problem tried the all the solutions no luck!!.

Resolution:

The problem found while installing I dint Selected the Products
       Web 2.0 HTTP Pub Servers and Weblogic Server Clients.
So I reinstalled without uninstllaing existing weblogic by selecting only previously unselected options (as above mentioned).

Now webserver onfigruration installed properly..

-:)