Hi Jackie,
Could you please perform the below steps?
1) Transaction SE51
Program SAPML03T, Screen number 0101 -> Element list -> Change
2) Select Tabstrip 'Special attr.', position the cursor on field LTAP-LGORT
and mark 'SET' parameter' and 'GET parameter'. Finally generate the screen.
Check this settings in your system and re-test.
BR,
Enrique