LTM error : LB_FAILED> - no such pool: invoked from within "active_members [LB::server pool]"

Hy guys, we are getting an error for the following iRule on LTM log and we do not understand totally what the issue is. Can someone help us out please ?

Feb xx xx:xx:xx4 xxxxx err tmm1[9887]: 01220001:3: TCL error: /Common/iRule_redirect_index_xxxxxxxx - no such pool: (line 2) invoked from within "active_members [LB::server pool]"

when LB_FAILED { log local0. "sedenueva_redirect_HTTP_REQUEST_LB_FAILED" if { ([active_members [LB::server pool]] == 0) and not($uri equals "/") }{ log local0. "sedenueva_redirect_HTTP_REQUEST_LB_FAILED no miembros" HTTP::redirect "https://$host" } }