you need to assign an instance of an object to the query variable before you can use it. Right now, you only declare a variable. Change the line:
Dim query AS CamlQuery
to
Dim query AS new CamlQuery
Also, CamlQuery expects a full <View>
tag. So change your CAML to <View><Query><Where><Eq><FieldRef Name='Account' /><Value Type='Text'></Value></Eq></Where></Query></View>
and you should be good to go.
If you wish to retrieve all items from the list, use the CamlQuery.CreateAllItemsQuery()
method.
Dim query AS CamlQuery = CamlQuery.CreateAllItemsQuery()