Problem during Subcontracting PO , components as " text item "

Hi experts ,

I've come across a strange problem during , BOM explosion in sub-contracting PO , - the components appears as " text item " ...

In, BOM creation I've maintained those components as stock item ( L) , and also, made the PO with stock item category  - but when , clicked on the components button , it displayed as "T" (text item ) ...

why it displays as " text item " and how could I change it to " L" ( stock item ) ? ...

regards

patel ...