sure it cannot work.
think logical:
your tray's direction is left
but you start in the label at x=0 y=0 ... so if it grows... it grows out of the image ;)

first of all, create label, your basic on the right side of the screen (labelx &resolutionx-"your label start width"$)
then positinate the tray's x coordiante (vtrayx $vtraylabelcurrentwidth-"iconsize+border"$)

the on add had to look like:

vTrayOnAdd !labelresize vtraylabel -"iconsize+border" 0
vTrayOnDel !labelresize vtraylabel "iconsize+boder" 0

*in your case iconsize+boder = 16+6 = 22 (6 px x-spacing?? issn't it too much?)