WS DIGITAL FILTERING ANALYSIS Transfer Function Frequency decimal precision

Hi everybody,
I am a problem with the decimal precision of the Low Cutoff Frequency and the High Cutoff Frequency in the transfer function "band-pass".
If I insert as Low cutoff frequency -> 0.005 and as High cutoff frequency -> 0.008 I have as a result the FIR functions = 0.
checking the log file I get the following:

"The following transfer functions are defined
  Transfer 1 - Band pass
    Low cutoff frequency : 0.00
    High cutoff frequency : 0.00"

Instead if I insert as Low cutoff frequency -> 0.005 and as High cutoff frequency -> 0.012 the log file I get is the following:

"The following transfer functions are defined
  Transfer 1 - Band pass
    Low cutoff frequency : 0.00
    High cutoff frequency : 0.01"

Now the question is: How can I work with low frequencies if the decimal precison is only 2? Is there any way to solve this problem?

Thank you in advance for your replies.

Regards,