Go undefined imported function

I have a problem using a function when there should not be any problem.
In Go, a Function that starts with a capital letter has a visibility outside the package.

node.go

package grid  

type Node struct {  
    id uint  
    name string  
    pos_i uint  
    pos_j uint  
    node_type string  
}

grid.go

package grid

/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    the Grid Structure
____________________________________________________________________________
*/
type Grid struct {
    // The numbers of divisions in the Grid
    number_lines uint
    number_columns uint 

    // The Sizes of the Grid
    width uint
    height uint

    // An Array of the Nodes
    nodes []Node
}

/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Initialize the Grid
____________________________________________________________________________
*/
func InitGrid() *Grid {
    g := new(Grid)

    g.number_lines = 4
    g.number_columns = 4

    g.width = 400
    g.height = 400

    return g
}

main.go

package main

import (
    "fmt"
    "grid"
)

/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Entry Point of the Application
____________________________________________________________________________
*/
func main() {
    grid_ := grid.InitGrid()
    fmt.Println(grid_)    
}

src/grid/Makefile

include $(GOROOT)/src/Make.inc

TARG=grid

GOFILES=\
    node.go\
    grid.go\

include $(GOROOT)/src/Make.pkg

src/main/Makefile

include $(GOROOT)/src/Make.inc

TARG=main

GOFILES=\
    main.go\

include $(GOROOT)/src/Make.cmd

When I compile the grid package, everything goes well, but when I try to compile le main package, it gives me that error message:

manbear@manbearpig:~/Bureau/go_code/main$ gomake  
6g  -o _go_.6 main.go  
main.go:15: undefined: grid.InitGrid  
make: *** [_go_.6] Erreur 1  

I don't understand why it gives me that error, I've passed some time reading the Go documentation, but I don't find the reason why it doesn't work.

Thank you for your help.

You compiled and installed the grid package with just the node.go source file. Compile and install the grid package with the node.go and grid.go source files. For example,

include $(GOROOT)/src/Make.inc

TARG=grid
GOFILES=\
	grid.go\
	node.go\

include $(GOROOT)/src/Make.pkg