Getting rid of 00:00 and Div/0 Errors on averages and totals when nothing entered

[aabbey]

Hello.
I am developing a log for RM recruits to help them log their injury rehabilitation, in an effort to assist them in seeing their own improvements to help boost both recovery and morale.
Most of the work is done although I keep getting DIV/0 errors and 00:00 on time totals when no info is entered. I can see why this has happening and I have attempted to use IFERROR however with no avail.

The cells causing me issue are listed below and attached is the file "Hunter Log" which contains the issue. I only require the issue solved on the sheet named Master

K&M 17
F-I 21
F-I 29 & I 29-39
F-I 41 & I 41-51

Yours Ever.

[PaulM100]

try: iferror(if(cell="","",your average()),"")

[Special-K]

Oops, posted in error, ignore this reply!

[aabbey]

I entered the forumula

=IFERROR(IF(cell="","",AVERAGE(H30:H39)),"")

In to cell H29 but it didn't work. The error has gone however entering data into the fields below doesn't yield an overall average in the previously stated cell.

[Sam Capricci]

how about simply =IFERROR(AVERAGE(H30:H35),"")
does that work for you?