DAX for between a date range Q

 would like to run my SUMX() with a FILTER() between a date range that I want hard coded. What I have doesn't work when I add in the between date range component. See code below:

EnquiryTest = SUMX ( FILTER ( '_enquiries,' '_enquiries'[_tsg_clientid_value] = 'accounts[accountid']) &&

'_enquiries'[Date] => {08/01/2018} &&

'_enquiries'[Date] =< {08/01/2018}, _enquiries[Amount (Enq)] )

What is the proper syntax for a between date range?

Thank you