Try to countifs and sumifs value with "-"

I have exported some value from MYOB, the accounting program, like this:

Column A Value Column A *1
6-1826 10 #VALUE!
6-1830 10 #VALUE! =COUNTIFS(A:A,">6-1825",A:A,"<6-1899") 3
6-1898 10 #VALUE! =COUNTIFS(A:A,">6-1900",A:A,"<6-1999") 0
6-1900 10 153
6-1910 10 3805 =SUMIFS(B:B,A:A,">6-1825",A:A,"<6-1899") 30
6-1932 10 11841 =SUMIFS(B:B,A:A,">6-1900",A:A,"<6-1999") 0
6-1951 10 18780


Column A is the account no. exported from MYOB.
Column B I assume each them is $10
Column C is column A*1
When I try to count or sum values between "6-1825" and "6-1900", it works perfect.
But when I try to count or sum values between "6-1900" and "6-1999", it doesn't work.

Can anyone please point out the problem, and how should I solve this?
Thanks a lot