Attribute value is not exported in PDML

Hello every body,

I wonder why in the PDML the attribute value is not exported when I do the following thing in the lua dissector:

subtree:add(f_sil, bit.band(buffer(3,1):uint(), 0x0F)) => no attribute value is exported in PDML for field f_sil.

When I do this, this works well (but not what I want): subtree:add(f_sil, buffer(3,1)) => atribute value is present in PDML.

Thanks in advance for any help.

Best regards.