Invalid use of null value Access 2007 -

i doing query when got invalid use of null value error:

select lansweeper_jacopobelloni.[numero inventario], cint([numero inventario]) espr1 lansweeper_jacopobelloni inner join pc_carelhq_modificato on cint(lansweeper_jacopobelloni.[numero inventario])=pc_carelhq_modificato.[n inv]; 

in lansweeper_jacopobelloni table primary key "numero inventario" text, doing cast on it, because in other table integer (it index there no decimal stuff).

i had 2 other alternatives make works.

i) select lansweeper_jacopobelloni.[numero inventario], val(nz(lansweeper_jacopobelloni.[numero inventario]," ")) espr1 lansweeper_jacopobelloni inner join pc_carelhq_modificato on val(nz(lansweeper_jacopobelloni.[numero inventario])," "))=pc_carelhq_modificato.[n inv];

which gives me mistake wrong number of arguments in val(..........)

ii) select lansweeper_jacopobelloni.[numero inventario], val(nz(lansweeper_jacopobelloni.[numero inventario],0)) espr1 lansweeper_jacopobelloni inner join pc_carelhq_modificato on val(nz(lansweeper_jacopobelloni.[numero inventario]),0))=pc_carelhq_modificato.[n inv];

which gives me same mistake i) !

thanks in advance.

the error message telling problem is. text column converting integer , using join fields problem - lansweeper_jacopobelloni.[numero inventario]

search nulls on column, or filter out in query before converting int.