WKM with iOSD need help with Height setup

[61retro]

Hi guys, I posted this question in another section of this forum, but it may be lost!! While I'm new to posting, I've been lurking for a while, and fly both the WKM and NAZA on quad/hex machines, and have gleaned much information from this group. I've decided to try FPV, and purchased a DJI iOSD for install in one of my quads. The issue that I have is that the height/altitude is not going to zero on the ground, and the "H" symbol is blinking continuously. I have reinstalled the firmware several times (version 2.0). I am using the SAO filter, and the unit is verion 1, vs MarkII. Everything else seems to be working perfectly. All of the videos that I have watched seem to have the height starting at zero. Am I missing something???? Thanks for all of your help. Regards. Mike Coletta