Page composer to copy the supplier site value to attribute4 field

I created a sandbx with page composer in the Enter Requisition Line UI. What i am trying to do is to copy the value of the supplier site to Attribute4 to do some validation.
I am using this code in attribute4 #{bindings.VendorSiteId.inputValue} in the Value field, but the problem is that the value being copied from the supplier site field to attribute4 is the LOV item id not the supplier site value, for example if i select the first value in the supplier site LOV the value copied to the attribute4 is 1 and if i select the second value in the supplier site LOV the value copied to the attribute4 is 2. What i need is to copy the value of the LOV for example if the supplier site value select from the