How to get ESLL-MWSKZ field given ESSR-LBLNI?

I'm trying to spot what Tax Code (ESLL-MWSKZ) was utilized fixed a database of work introduction expanse numbers (ESSR-LBLNI). 

SE16N array ESSR - I participate the Service Entry Sheet fig into ESSR-LBNI and I get the associated ESSR-PACKNO. Then, SE16N array ESLL and participate the ESSR-PACKNO into ESLL-PACKNO and get an output... but ESLL-MWSKZ displayed is blank!

Manually looking I tin intelligibly spot that the Tax Code for the work introduction posting not blank, and it's expected to beryllium ESLL-MWKZ... but viewing array ESLL, pulling it up the mode described above, it's blank successful the array output display!

Any assistance would beryllium appreciated!

ESLL show from with entering PACKNO from ESSR into PACKNO for ESLL:

what the taxation codification really is, erstwhile I show the introduction sheet: