C - Macro problem with nested structures

[Cagin]

I define a macro like this:

#define L(p) ((p).value.len)

typedef struct node
{
	int dimension;
	int position;
	int size;

	union 
	{
	    long len;
	    float f;

	    } value;

	struct node *prev;
	struct node *next;

} node, *np;

and later,when I try to use that macro,
I have this error:
"error:requ est for member 'value' in something not a structure or union "

So can you please help me to fix this problem?
Is there any other way to define macros for nested structs?

[Banfa]

We need to see the code that uses the macro as in addition to what you have already posted.

But my guess is that you have passed a pointer to your macro which is expecting a structure.

[Cagin]

Yeah, you are right. I used to have a pointer problem, I fixed it. Thanks for help.