Iserror works on one column but not two in small nested formula

Hello People..
I'm trying to get Iserror to ignore #N/A errors from a chart data area. I'm wanting to count the number of times in a row something happens, that bit I can do. I'm trying to get Iserror to ignore the errors in columns KE6:KE51 & KF6:KF51. I can only get it to ignore one column or the other, not both at the same time. I need to combine the occurrences of "1" in both columns & have them appear in column KB if they are in the other columns. If not leave the cell blank. I'm having to do this as counting a run of entries doesn't work with errors in the column. Hoping this explanation is clear enough
I've attached an example
Any ideas please.
Thanks