Status change from H1B to H4

I filed to change my status from H-1B to H-4 on September 10, 2003. Today, I received a letter from Immigration Service and they want evidence that I was maintaining valid H-1B status until September 10, 2003. Actually, I didn’t go to work with my sponsor company for one year (from September 11, 2002 to September 10, 2003). The company gave me a letter of “leave of absence” for one year and kept my H1B visa valid until September 10, 2003. My questions is: can I give Immigration Services the letter of “leave of absence” (from September 11, 2002 to September 10, 2003) as an evidence that I was maintaining valid H1B status until September 10, 2003? Does anybody have similar experience or have any comments on that? Thanks a lot.