C :: Passing 2D Array To A Function

I need to pass a 2D array to a function. I want to know, where I may have made a mistake. This is the piece of code that I found on the web, and I am using it to allocate my 2D array.

Code:
signed char allocate2D( int** arr2D, int rows, int cols )
{
int i;
arr2D = malloc( rows*sizeof( int* ) );
if( !arr2D )
return -1;

[Code]....

My main function passes the 2D array to the function

Code: signed char read_root_message_file( int **Root_Messages, int *num ) This is how I pass the array in the main function to the above function:

Code:
int main( int argc, char *argv[] )
{
int **Root_Messages;
...
...
Root_Messages = NULL;
read_root_message_file( Root_Messages, &num_root_msg );

[Code]....