Excel 2010: The dredded #DIV/0! error

Hi there.
I am using Excel 2010.

I am trying to calculate the profitmargin in percentage for several companies for a comparison.

I find the (salesprice - cost price = profit)
And after that i find the profit divided on sales prices multiply 100 is profitmargin in percentage.

But, if the sales price is zero, I get the error #DIV/0!

I have already googled and tried several solutions.
Like:
=IF(ISERROR((E7-C7)/E7*100),"",(E7-C7)/E7*100)
=IF(E8=0,"",((E8-C8)/E8)*100)
and some more...

If I write #N/A I get #VALUE!


I have the following columns: sales price, cost price, profit in percentage.

Any clue on how to NOT get those errors in those cells with out a value.
The cost price will always be there, but sales price is only if the company have bought it.

I am losing my mind over this...

You could try this one.
=iferror(IF(ISERROR((E7-C7)/E7*100),"",(E7-C7)/E7*100);"")

Nope, got a error message stating: "It is something wrong with your formula".

Trying the next...

Nope, the same error on that too.

Like L-Drr

I see you used semi commas, I used only commas.
=IF(B4=0;"";(B4-$A4)/B4)

But, works, like a charm now.

Super thanks...
I am very grateful for the help.