I94 not changed at Port of Entry

[junk_nare]

Need some help here, couldn't find answer any where.

I and my wife went to Bahamas in the month of March-2012 for my Anniversary through a Cruise ship. We had a valid visa to Bahamas and Visa stamped passport to enter back to United States(till Oct 2012).

Generally when we travel out of country they take our I94’s and issue a new one at the port of entry when we come back to US.

• To my surprise immigration did not stamp a departure stamp (on my passport) while leaving the port and no arrival stamp when I came back to the Charleston Port of Entry.
  
• They did not take my I94 card while leaving and did not issue me a new one when I came back.
  
• In Bahama's there was no Port of entry or exit so no immigration stamping at all.
  
• So there is no proof that I traveled to Bahama's at all
  

I know have a visa extension and my wife is filing for H1B from H4. while filling the petition application questioner

What should be my answer to below questions?

· What is the last arrival date to United States?

· What document did you use to enter to United States?

· What is document number used (I94)?

If I say the last arrival date in March 2012(my bahama return date) my I94 number would not match to it?

Can some one help on this scenario, please.

[junk_nare]

Moving this post up for the answers