Failed to add WebRole with virtual network configuration

Hello.

When I trying to add a "WebRole" through the management portal (upload a package with configuratioln file in the Cloud Services) I get the following error: 

A virtual network site cannot be added or removed during deployment update or upgrade.

But other role "WorkerRole" works fine when I use the same network configuration settings

My WebRole name is "DeviceEntryPoint" and this is the network configuration:

<NetworkConfiguration><VirtualNetworkSite name="MYVNET"/><AddressAssignments><InstanceAddress roleName="DeviceEntryPoint"><Subnets><Subnet name="AppSubnet"/></Subnets></InstanceAddress></AddressAssignments></NetworkConfiguration>

My WorkerRole name is "EntryPoint" and this is the network configuration:

<NetworkConfiguration><VirtualNetworkSite name="MYVNET"/><AddressAssignments><InstanceAddress roleName="EntryPoint"><Subnets><Subnet name="AppSubnet"/></Subnets></InstanceAddress></AddressAssignments></NetworkConfiguration>