Windows 7 remote assistance credentials prompt issue

When connecting from my win7 PC to another win 7PC on our domain where the user of the traget PC does not have admin rights and I want to preform an admin function the user sees a credentials prompt window, but on my end the screen goes black with two large vertical white bars. Any ideas why  the credentials prompt window is not visible or accessible to me remotely so I can enter the admin credentials?
I have have local admin rights on my PC and the target.
Permissions, settings or display issue ?
Many Thanks!
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You can't enter credentials into the UAC box because that ability is the very permission that you are requesting when you request admin function.  The user will have to perform this for you.  Setup a temp admin account for this purpose.
rnolan123Author Commented:
Yes that makes sense, but our users are not allowed local admin access of any kind on thier PCs.
If I connect with LogMeIn I can see the credentials prompt window and enter them in remotely, but not when I use Windows Remote Assistance. Almost seems like a display graphics issue...
depending on what it is you want to do, you could always open a command windows in which you can elevate your rights: runas /user:<administrative_account@domain> cmd
this will open a new command windows with elevated rights.
make sure to exit the command window prior to terminating the session.

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