Rezzers Common Problems
Before rez / at time of rez :

• The structure is scrunched against the ground.

If the pieces would end up below the ground, they'll "give up" and sit at ground level.  Move or rotate
the rezzer to lift them out.

• The structure is scrunched against the sim border.

If you're at the very edge of the world, the pieces may try to fall off into the void, but they'll stop
themselves before they go that far.  Move or rotate the rezzer away from the edge of the
world to fix this

• I lost a piece of the structure!

If your pieces end up over a neighbor's plot with auto return on, they may return to your inventory.  
Just De-rez the structure, move the rezzer, and re-rez it.

• Rezzer don't work or,  menu does not appear at all!    

Make sure YOU have build powers on the land, that there are prims available for build, make sure SCRIPTS ARE ENABLED in the land.
If not sure about any of those, please ask your landlord (inform him/her this is a REZ FAUX rezzer, that requires scripts enabled in order to run )