Filtering data based on manual dates entered.

Ok, another question here.  I feel I am in the ball park.  I am trying to sort my data based on when clients were terminated.  However, those dates I want to use can always change based on what information I want to pull, so I didn't want to put any static formula in place.  So created two date fields that a user can use to filter for dates.  I have tried using the following formula with no luck.

let startDate := date('Beginning Date');
let endDate := date('End Date');
count((select Clients)['Pretrial Termination Date' = (>= startDate) and 'Pretrial Termination Date' = (<= endDate)].'Termination Reason' = 1)

Beginning Date is the manual start date field

End Date is the manual end date field.

Clients is the Parent Table.  

Termination Reason =1 are all sentenced clients

Pretrial Termination Date is a field that is on every record where a date is put in when a client is terminated.  

Any help is greatly appreciated.  Thanks!