The following code gives an error, my goal is to draw 4 different arrows but only three functions successfully.

The error log shows

metapost        > initializing number mode 'scaled'
metapost log    > 
metapost log    > loading metafun, including plain.mp version 1.004 for metafun iv and xl
metapost log    > 
metapost log    > >> unknown path D
metapost log    > ! Isolated expression.
metapost log    > <to be read again> 
metapost log    >                    :
metapost log    > <*> ... :=(12cm, -1cm)--(11cm, -1cm); path D ; D :
metapost log    >                                                    =(4cm, -1cm)--(3cm, -1cm)...
metapost log    >

And the code is as follows

\startMPcode 
path A ; A :=(0cm, -1cm)--(1cm, -1cm);
path B ; B :=(13.5cm, -1cm)--(14.5cm, -1cm);
path C ; C :=(12cm, -1cm)--(11cm, -1cm);
path D ; D : =(4cm, -1cm)--(3cm, -1cm);
drawarrow A; drawarrow B; drawarrow C ; drawarrow D ;
\stopMPcode

Unless I uncomment D it gives the above error.

Mysterious issue

/Janne