How to select a range of dates

Hi
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I am trying to select data for a range of dates using
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{ data } shows those two nmDate values as [nmDateFrom] => 2019-01-01 and [nmDateTo] => 2019-01-31
bur when i run the selection I get
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0 - key() expects parameter 1 to be array, null given

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It works fine with a single date selection
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SELECT `mdlMbrReceipts`.`idReceipt` AS `mdlMbrReceipts.idReceipt`, `mdlMbrReceipts`.`feeYear` AS `mdlMbrReceipts.feeYear`, `mdlMbrReceipts`.`feeToPay` AS `mdlMbrReceipts.feeToPay`, `mdlMbrReceipts`.`receiptType` AS `mdlMbrReceipts.receiptType`, `mdlMbrReceipts`.`user_id` AS `mdlMbrReceipts.user_id`, `mdlMbrReceipts`.`lastname` AS `mdlMbrReceipts.lastname`, `mdlMbrReceipts`.`firstname` AS `mdlMbrReceipts.firstname`, `mdlMbrReceipts`.`dateReceived` AS `mdlMbrReceipts.dateReceived`, `mdlMbrReceipts`.`accountPaid` AS `mdlMbrReceipts.accountPaid`, `mdlMbrReceipts`.`datePaid` AS `mdlMbrReceipts.datePaid`, `mdlMbrReceipts`.`payReceivedById` AS `mdlMbrReceipts.payReceivedById`, `mdlMbrReceipts`.`paidBy` AS `mdlMbrReceipts.paidBy` FROM `u3a_00_receiptsmembership` AS `mdlMbrReceipts` WHERE `mdlMbrReceipts`.`datePaid` >= '2019-01-01' ORDER BY `mdlMbrReceipts.datePaid` DESC, `mdlMbrReceipts.paidBy` ASC, `mdlMbrReceipts.idReceipt` ASC LIMIT 20;

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I have tried to change those date selectors to mySQL dates but the same problem. And I have tried with just that dateTo value. Again - on its own - fine! and the SQL above woth both dates in works fine with phpMyAdmin
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Any suggestions??
Regards
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Nick