ipc share error!access deny

[net2net]

target 192.168.245.145 os is win7
and mypc is also win7

D:\security\Tools>net use \192.168.254.145\admin$ admin /user:WIN-8KJMMFIL6HF\a
dministrator
命令成功完成。

success!!!

D:\security\Tools>net use \192.168.254.145\admin$ /del
\192.168.254.145\admin$ 已经删除。

=======================================================

D:\security\Tools>net use \192.168.254.145\admin$ admin /user:WIN-8KJMMFIL6HF\a
dmin
发生系统错误 5。拒绝访问。
access deny!

failed!!!!

admin blong to administrators group,but ,administrator can ipc share ,admin cant !!!

why ? thanks!