Error when saving postion offsets in the offsets tab

Hey peeps. I have searched the Internet and cant find an answer. I have hooked up absolute encoders and when I try to save the current position G54 on the offsets page I get the error bad character a used. Any idea what's going on? I can losd the table and clear it, but cant save it. 

Not sure if this is a pb thing or a linuxcnc thing. I read that when himing for the first time with absolute encoders i need to save the home position by zeroing the axis and saving the cirrent position to the offsets tab.

Many thanks 

If you have an "a" axis specified in the ini anywhere, But do not have an "a" axis actually configured in hal you will get the error as its trying to store a position for an undefined axis.

Would be my guess of the error condition