Linux Kernel Message Queue Implementation

[1] msgsnd (int, struct msgbuf *, int, int) INTERFACE ERROR !!

[2] msgsnd() has "struct msgbuf*" as its 2nd parameter. When I tried to write an application which uses message queues for IPC i declared my message queue buffer as -

struct my_msgq_buf
{
    long mtype;
    char *name;
    double amount;
};

I allocated the memory of name dynamically using "malloc" and wrote into the message Queue using msgsnd. And the msgsnd returns successfully. When I do an msgrcv with the above structure type, I always recieve NULL values in my structure buffer !! 

But, When I use the structure as declared below -

struct my_msgq_buf
{
    long mtype;
    char name[30];
    double amount;
};

Every thing interstingly seems to be working fine.! The interface for msgsnd and msgrcv should have "void *" pointers rather than having a "struct msgbuf *" as parameters.

[3] Kernel
[4] 2.4.7-10 
[5] 
[6]
[7] i586. Intel Pentium 166 MHz MMX.
[8]