Receive Fax in asterisk , but cannt get actual pic in tiff

I have use fax mechine fax to my DID in asterisk. I can get the Tiff file but Tiff file is blank. Can anybody give me some help. I am using Ulaw.

The two ends not negotiating properly, old dumb fax machine, could be a few things. Would need more info other than this doesn’t work. Start by examining the players involved. Test send from different fax machine etc.