Hi. It took a while to get an answer back. I found my own way to do this while waiting for the reply. It's probably not ideal, but it got the job done.
In the record selection Formula I typed in the following statement. I think I have all my bases covered with an if..then else.. if ... then.
if( {?Customer Number} <> "All Customers") and
( {?Location} = "All Locations")
then
( {Command.CUSTOMERNO} like {?Customer Number} ) and
{Command.DATECOMPLETED} = {?Date Range}
else
if( {?Customer Number} <> "All Customers") and
( {?Location} <> "All Locations")
then
( {Command.CUSTOMERNO} like {?Customer Number} ) and
( {Command.LOCATION} like {?Location} ) and
{Command.DATECOMPLETED} = {?Date Range}
else
if( {?Customer Number} = "All Customers") and
( {?Location} <> "All Locations")
then
( {Command.LOCATION} like {?Location} ) and
{Command.DATECOMPLETED} = {?Date Range}
else
{Command.DATECOMPLETED} = {?Date Range}