ROCKPOS Module Error on Sales

[samzee]

Does anybody here knows how to get rid of  an error with a POS module ? , I install the module just fine, the manage section is working but after i click on sell  the page goes into a blank screen spinning ball of death.

 

error on chrome developer console:

 

Uncaught TypeError: Cannot read property 'style' of null

    at t.value (sales.js?v=1500233978:109)

    at Object.r (sales.js?v=1500233978:86)

    at a (sales.js?v=1500233978:86)

    at Object.s [as executeDispatchesInOrder] (sales.js?v=1500233978:86)

    at p (sales.js?v=1500233978:15)

    at g (sales.js?v=1500233978:15)

    at Array.forEach (<anonymous>)

    at n (sales.js?v=1500233978:108)

    at Object.processEventQueue (sales.js?v=1500233978:15)

    at r (sales.js?v=1500233978:126)