different result formula if using google spreadsheet and excel

I am having trouble understanding the IF statement. What I am trying to do is: 1. in excel , i am using formula =IFERROR(IF(A1+1<=$B$1,A1+1,""),"")

2. in google spreadsheet, i am using the same formula like excel =IFERROR(IF(A1+1<=$B$1,A1+1,""),"")

but result that is different, how can i get result in google spreadsheet like result in excel. thanks