[exim] Problem with smtp_load_reserve

Hi

is there some way that this phrase could work?

NET_SUBMISSION = 11.22.33.44
smtp_load_reserve               = ${if match_ip 
{$interface_address}{NET_SUBMISSION}{70}{40}}

2015-03-16 14:21:53 Exim configuration error in line 155 of
/etc/exim4/conf.d/main.conf:
fixed-point number expected for smtp_load_reserve


Regards