How to solve the error "permission to perform this operation was denied"?

I am trying to convert a windows server 2008 R2 using vCenter, but getting "permission to perform this operation was denied"

I had successfully converted several windows servers 2008 before, using the same process.

After digging the internet i found several solutions:

1) Adding the user to the local administrators group on both the source and destination servers.

2) Running the software as an administrator (right click > run as an administrator).

I have tried both options, yet i still get "permission to perform this operation was denied". I am running vCenter from a windows 7 computer which is part of the domain and the account is part of the local administrators group. Same account is part of the windows server Domain Admins group and local Administrators group.

Any ideas on how i can solve this error ?

Any help is greatly appreciated.

Thanks in advance!