DNS forwarder - Override entire domain

Hi,

I'm trying to override my ISPs DNS servers for my company's domain using 
the DNS forwarder. I have an IPsec VPN configured betweem my home and 
the company so I can access the company's internal DNS server (it is not 
accessible via the internet) but unfortunately it doesn't seem like the 
DNS forwarder is able to access the company DNS server through the 
tunnel. If I query the company DNS server directly with nslookup I'm 
able to get proper responses through the tunnel but if I do it through 
the DNS forwarder it doesn't work.

Is this a limitation of the DNS forwarder or is there something I'm missing?

Thanks,
Kim