ERROR with Event report with condition checkbox

Hi all,
currently, i am using DHIS2 V2.20

but the problem with check box true/false of data element in tracker.

if i use event report to filter with check box value, it does blank screen, but if i didn’t put filter with data element has check box value, i can see data value.

do you know what is the problem? Even i do with web API, i meet the same problem…

result no filter value with data element has check box

result with filter value with data element has check box (ERROR)

thank you

channara