Help with ESXI and Sophos

hello every one 

iam trying to install the UTM on ESXI 6 but i faced some problem which i need help with 

first of all, i have 

One Dedicated server with ONE lan card

one Cisco swith SF200 - Managed switch 

3 ISP Connection 

what i want to achieve..

create LoadBalance on the ISP connections using the firewall 

apply speed limit on one of the vlans - Hospital users

apply another speed limit on another vlan - Guest Users

so ..

i created three vlans on cisco swith 

vlan 10 - for the wan links

vlan 20 - for hospital users 

vlan 30 - for the guests 

and this is my configuration on the ESXI host

i created three switches on the ESXI with vlan tag for each one

and created 4 interfaces for sophos

one on untagged switch for managing

one on vlan 10 switch for the wan links

one on vlan 20 switch for hospital users - with network 10.10.10.0/24

one on vlan 30 switch for guests users - with network 10.10.50.0/24

i could access the web interface via manage interface with no problem 

now i want to add the vlan on the sophos so i i can apply rules on each vlan 

i tried to add the interface directly as "Ethernet"and gave it IP

and i could ping on it succefully via the domain which i assigned it on the same vlan 10 switch

but when i deleted the interface and assigned it as "Ethernet Vlan" i couldnt ping on it 

so 

any ideas about how to configure it probably

thanks in advanced