The command eval dtxr for all from !bmem returns you an Array with the dtxr value of each element included in your Array !bmem. In your Handle, you give it a simple String instead, which doesn't work.
The most suitable would be to loop through !bmem and handle your error in your loop. Something like this:
!dtxrs = ARRAY()
Do !member values !bmem
!dtxr = DTXR of $!member
HANDLE ...
!dtxr = 'NA'
ENDHANDLE
!dtxrs.append(!dtxr)
Enddo
