Remote WMI Connection issue

Question

i needed to get the free disk space on a shared remote drive.
my shared-name goes something like this -- \\RemoteServer\ADrive$

ConnectionOptions oConn = new ConnectionOptions();
oConn.Username = "xUser";
oConn.Password = "xxxx";
string sSrvName = @" \\RemoteServer\ADrive$";

ManagementScope oMS = new ManagementScope(sSrvName, oConn);

I get the error  - "Invalid Parameter".
If i remove the $ sign from the end of the server name and make it something like \\RemoteServer\ADrive
it goes past the above statement and fails  at
ManagementObjectSearcher oSearcher = new ManagementObjectSearcher(oMS, oQuery) ;
ManagementObjectCollection oReturnCollection = oSearcher.Get() ;

with the error -  "RPC server is unavailable"

but when trying to map the above mentioned share drive - \\RemoteServer\ADrive$, via Windows Explorer it works.
any kind of help is appreciated.

thanks to all