A few possibilities:

1) The statement date controls which transactions print on the statement, along with the option to print 'Outstanding transactions only'. If the invoice has a date of April 28, it will not print if the statement date is prior to then.

2) When printing statements, you can choose to select customers that have a positive, negative and/or zero balance. Ensure that you have the desired selection for this customer, based on their balance as of the statement date.

3) This customer is defined to not accept statements with that print method. Edit the customer and on the Statements tab, determine which of the print, fax or email they are allowed to have.

If you are printing statements as a date after April 28, and you have the correct customer balance selection, and the customer is allowed to get statements with the used print method, then please indicate what all of the options you have selected for the statements, and what the customer balance and statement print status is.