[6d]

I agree with you, Programming is case sensitive.
let's see a example,
if you put this:

pawn Код:

#include <a_samp>

#define MessageOfTheDay "Welcome to SA:MP Forums!"

main()
{
    printf("Message of the Day: %s", MessageOfTheDay);
}

it should run perfectly, notice that letters M-O-T-D are capitalized in the word MessageOfTheDay.
Now if you put this:

pawn Код:

#include <a_samp>

#define MessageOfTheDay "Welcome to SA:MP Forums!"

main()
{
    printf("Message of the Day: %s", messageoftheday);
}

it will give the following errors:

Код:

error 017: undefined symbol "messageoftheday"

which simply means, that the system will not recognize it as a declared variable.

but well, hope this explains why it was a error.

it's SetVehiclePlateNumber