Sum+IFERROR Help

Okay Guys,

I just had help on something similar I found it so useful I wanted to implement it on a different worksheet thought I could figure it out , but no go. Anyway I want cell w12 to read nothing when cell o12 has any integer including 0 in it howver when cells o12 p-u12 and v12 have something in them I need it the formula 012+p12:u12-v12 to come up now there may only be 1 cell between
p12:u12 that hasa number. If thats too confusing which I'm sure it is i can better try to explain and attach a workbook.

Right now Ihave this
=IF((SUM(O13:U13)-V13)=0,"",IFERROR(O13+P13+Q13+R13+S13+T13+U13-V13,""))
but when cell o13 has a number and nothing else does it reads that number if only o13 has a number I need it to read nothing.

Any Help Appreciated,

CW