Trouble with iserror 508 error

I have trouble with function
Calc says me that there are Err:508.
And in case IF(ISERROR(D6/B5);0;(D6/D5)) pushing 0 an all input data.

I can`t user IFERROR becouse APACHE poi (3.14) export crashes on it.
Please, Help me.

Please, try change comma to semicolon. When I type your formula I get Err:508 too. But after change it to =IF(ISERROR(D6/B5);0;(D6/D5)) I get zero too. But after filling cells B5, D5 and D6 with non-zero values I get real value… By the way, you calculate the error for B5 and calculate the fraction of D5. It is right? Perhaps it suffices to verify the divide by zero?