Query times out when I add extra Where Condition

[John Noble]

I have a query in a stored Proc.

-- Payments WIth Balances
SELECT salesledger.customerID as customerID,
salesledger.countryID as countryID,
salesledger.invoiceDate as InvoiceDate,
salesledger.dueDate as dueDate,
salesledger.invNum as invNum,
if (p_sterling = true, "GBP", salesledger.invoiceCurrency) as invoiceCurrency,
salesledger.CCmanagerID as CCmanagerID,
if (p_sterling = true, round(salesledger.payable / salesledger.conversionRate, 2), salesledger.payable) as payable,
salesledger.paidToDate as paidToDate,
if (p_sterling = true, round(salesledger.net / salesledger.conversionRate, 2), salesledger.net) as net,
if (p_sterling = true, round(salesledger.vat / salesledger.conversionRate, 2), salesledger.vat) as vat,
if (p_sterling = true, ifnull(round((salesledger.payable + sum(receipts.allocationAmount)) / salesledger.conversionRate, 2), round(salesledger.payable / salesledger.conversionRate, 2)),
ifnull(salesledger.payable + sum(receipts.allocationAmount) , salesledger.payable)) as balance,
salesLedger.freshFrozen as freshFrozen,
customers.name AS cname,
customers.telephone as ctelephone,
ifnull(customers.groupID, "") as cgroupID,
ifnull(groups.name, "") as groupName,
ifnull(users.name, "") as username,
countries.name as countryName,
p_date as selectedDate
FROM salesledger
LEFT JOIN receipts ON
salesledger.paymentNo = receipts.paymentNo
LEFT JOIN customers ON
salesledger.customerID = customers.customerID
LEFT JOIN groups ON
customers.groupID = groups.ID
LEFT JOIN users ON
salesledger.CCmanagerID = users.userID
LEFT JOIN countries ON
salesledger.countryID = countries.countryID
WHERE
salesledger.docType = "PAY"
and salesledger.invoiceDate <= p_date
and (salesledger.paidInFullDate = '0001-01-01' or salesledger.paidInFullDate > p_date)
and salesLedger.freshFrozen <> p_freshFrozen
GROUP BY
customerID, invNum, invoiceDate, payable


This works fine and is reasonably quick.

When I add the condition 'and receipts.invoiceDate <= p_date' to the Where statement the it times out. I have even added an index on receipts.invoiceDate but it has made no difference.

Any ideas on how to solve this ?

John