VBO cannot be deleted?

Hi,

GLuint a,vboID;
	GLubyte *pointer;
	
	glGenBuffersARB(1, &vboID);
	glBindBufferARB(GL_ARRAY_BUFFER_ARB, vboID);
	glBufferDataARB(GL_ARRAY_BUFFER_ARB, sizeof(packet_payload), packet_payload, GL_DYNAMIC_DRAW_ARB);
	glBindBufferARB(GL_ARRAY_BUFFER_ARB, 0);

	glBindBufferARB(GL_ARRAY_BUFFER_ARB, vboID);
	pointer = (GLubyte*)glMapBufferARB(GL_ARRAY_BUFFER_ARB,GL_READ_ONLY_ARB);
	
	printf("Payload:");

	int p=0;

	for(a=0;a<noOfpacket*2048;a++)
	{
		printf("%c",pointer[a]);
		p++;
		if(p==2048)
		{
			printf("
");
			p =0;
		}
	}

	glUnmapBufferARB(GL_ARRAY_BUFFER_ARB);
	glDeleteBuffersARB(1, &vboID);

Why i cannot delete the vbo even though I have use glDeleteBuffersARB here? I check already. When I change send a new data into the VBO again and read it out, the data still contains the previous data. Just the current data has replace some of the previous data.

Sry…problem solved…