case background：have a excel tool，need to write data into PI system by excel tool, "the PI point had build in the PI system, the point have no OPC deveice"
case describe：write data into PI by excel，submit , input user name and password , A dialog box appears “-2147220478 Unable to open a session on a server.[-10431] Authentication method is disabled by current policy”：
Try to solve the way：
1. Check the Client About SDK, the user name is "piadmin";
2. Check on the PI server, confirmed the client Trusts have added，and displayed "piadmin"。
3. Changed the piadmin password from PIserver, "PIserver/Security/Users", change piadmin password，the password changed sucessful, then test the excel tool on client machine,the error dialog appears again;
4. Check the PI point attribute from PIserver, "Piserver/Data/input the PI point / point attribute" check the PI point security attribute（datasecurity&pisecurity），confirmed the user "piadimin" have "Read" and "Write" function。
the error message following the picture: