Does not work with "Number Field" about link_preview HOT 10 CLOSED

Array
(
    [show_column] => yes
    [allow_override] => no
    [fetch_associated_counts] => no
    [hide] => yes
    [id] => 14
    [label] => Titel
    [element_name] => titel
    [type] => reflection
    [parent_section] => 5
    [required] => no
    [sortorder] => 0
    [location] => main
    [field_id] => 14
    [xsltfile] => 
    [expression] => {substring(entry/zeitraum/date/start, 1, 4)} KW {entry/wochen-nr}
    [formatter] => none
    [override] => 
)

Array
(
    [show_column] => yes
    [allow_override] => no
    [fetch_associated_counts] => no
    [hide] => yes
    [id] => 16
    [label] => Jahr
    [element_name] => jahr
    [type] => reflection
    [parent_section] => 5
    [required] => no
    [sortorder] => 1
    [location] => sidebar
    [field_id] => 16
    [xsltfile] => 
    [expression] => {substring(entry/zeitraum/date/start, 1, 4)}
    [formatter] => none
    [override] => 
)

Array
(
    [required] => yes
    [show_column] => yes
    [id] => 15
    [label] => Wochen-Nr.
    [element_name] => wochen-nr
    [type] => number
    [parent_section] => 5
    [sortorder] => 2
    [location] => main
)

Array
(
    [pre_populate] => now
    [required] => yes
    [location] => sidebar
    [show_column] => yes
    [id] => 13
    [label] => Zeitraum
    [element_name] => zeitraum
    [type] => datetime
    [parent_section] => 5
    [sortorder] => 3
    [field_id] => 13
    [prepopulate] => 0
    [time] => 0
    [multiple] => 0
    [range] => 1
)

Array
(
    [required] => no
    [show_column] => yes
    [id] => 12
    [label] => Nr.
    [element_name] => nr
    [type] => incremental_number
    [parent_section] => 5
    [sortorder] => 4
    [location] => main
    [field_id] => 12
    [start_number] => 1
)

Array
(
    [required] => no
    [show_column] => yes
    [id] => 50
    [label] => Frontend
    [element_name] => frontend
    [type] => link_preview
    [parent_section] => 5
    [sortorder] => 5
    [location] => sidebar
    [field_id] => 50
    [format] => /{$jahr}/{$wochen-nr}/
    [anchor_label] => Frontend
    [display_url] => yes
)