Are the Win7 clients 64bit? Just thinking it may not work on 64 bit.
Gateway and subnet mask are correct, though I don't know if you can set them with the CMAK kit. That was why I thought it was worth trying.
-Mask is always 255.255.255.255 (indicates 1 IP only)
-If Gateway is set to 0.0.0.0 it means "use remote default gateway" is checked. 0.0.0.0 = all thus send all traffic via the PPP adapter
[If gateway is set to the same IP as the PPP/VPN adapter (10.1.1.1 in your case) it means "use remote default gateway" is not checked. Send only 10.1.1.0/24 traffic via the PPP adapter