Attempt to add part at undefined sensor 1 on conveyor coneyor001？

dd13616

Attempt to add part at undefined sensor 1 on conveyor coneyor001是怎么回事？

conveyor元素的input rule：
if nparts(coneyor001)<5
pull from buf1 with labor1 using path
5 [1 j; H+ z3 w3 U4 Pelse
: K. |: J. D+ I! Await
7 A, F- V, p1 V: \endif