Updating I/O field in PBO

After the selection screen, I've got an ALV that shows the info + 2 icons:

I've got some actions for the 2 icons. The last one set values for TOP variables and call new dynpro (1300), I need to fill the 1300 dynpro fields with this info but when i try to refresh the values on the 1300 PBO selection data (for example set T_MATNR field 'EXAMPLE' value):

It shows this error:

But the fields exists:

What I'm doing wrong?