There's no action in that script telling the item to be picked up by the player, and also you fpi files aren't supposed to be put in an ifused parameter. The stock dossier comes with a pickup script which should work for you.
EDIT: Just re-read your post, did you mean the text should show when the dossier has been picked up? If so, name the trigger zone textshow. In the dossiers IfUsed properties, set it to textshow. Set the following script to be the dossier's main script:
:state=0:hudreset,hudx=50,hudy=90,hudimagefine=gamecore\text\pickedupanitem.tga,hudname=itemprompt,hudhide=1,hudmake=display,state=10
:state=10,plrdistwithin=40:state=1,activateifused=1,playertake,coloff,plrsound=audiobank\misc\ping.wav,hudshow=itemprompt,hudfadeout=itemprompt
:state=1:rundecal=5
Now set the main script of the trigger zone to the one below:
:state=0:hudreset,hudx=50,hudy=90,hudimagefine=gamecore\text\Dossier01.jpg,hudname=yourhud,hudhide=1,hudmake=display,state=1
:state=1:activated=1,state=2
:state=2,plrwithinzone=1:hudshow=yourhud,state=3
:state=3,plrwithinzone=0:hudunshow=yourhud,state=2
FPSC MIGRATION: http://bit.ly/5I8LYO
FPSC NUCLEAR EXPLOSION: http://bit.ly/67v8GI