Recipient of my form says fields are blank

Hello. I have a form created with LiveCycle Designer that I use as an order form. I fill out the fields myself in Acrobat 9 Pro, save a copy of the form and e-mail it to various vendors. Generally, the form works great. However, one particular vendor says that when they open up my form, the fields are blank. I am sure I e-mailed them a completed form, but if they e-mail it back to me, the fields are indeed all blank. They have a Mac running Acrobat 8 Pro and a PC running some version of Reader and say this problem occurs with both computers. Any thoughts? Thank you much.