dear colleagues I am trying two create a bar graph with two y-axis from my data and code below and am getting error "invalid span'.What does this mean?Can I get an assistance kindly
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input byte(Poulation Tube_conc Flow_rate) int(Low_EventRate High_EventRate No_cellsSeen) byte Sort_Duration float seen
1 1  1 1200 1500  5423 11 2
1 1  3 1000 1300  3460  5 2
1 1 10 2000 2300  9163  6 2
1 2  1  400  500  5941 13 2
1 2  3  170  300  3899 12 2
1 2 10  300  600  5394 11 2
1 3  1  250  300  4857 81 2
1 3  3  120  300  4696 67 2
1 3 10  250  400  8529 47 2
1 1  1 1200 1500  5968 11 1
1 1  3 1000 1300  3800  5 1
1 1 10 2000 2300 10478  6 1
1 2  1  400  500  6051 13 1
1 2  3  170  300  4157 12 1
1 2 10  300  600  6051 11 1
1 3  1  250  300  4839 81 1
1 3  3  120  300  4656 67 1
1 3 10  250  400  8591 47 1
end
label values Tube_conc mea
label def mea 1 "20k cells/ul", modify
label def mea 2 "5k cells/ul", modify
label def mea 3 "1k cells/ul", modify
label values seen s
label def s 1 "seen", modify
label def s 2 "sorted", modify
------------------ copy up to and including the previous line ------------------

Listed 18 out of 18 observations



twoway bar No_cellsSeen, ///
over(Flow_rate,label(labsize(small)) gap(10)) ///
over(Tube_conc, label(labsize(small)) relabel(`r(relabel)')) ///
ytitle("Number seen/sorted", size(small)) ///
yaxis(2) ///
, span size(medium)) ///
blabel(bar,position(top)) ///
intensity(40) bgcolor(white) ///
asyvars ||
twoway bar