[Serusers] Avpops: avp_op() function

Hi all, i'm using openser 1.0.0. I'm trying to use avpops' avp_op() function to add 100 to the Cseq value (just to test the avp_op() function). Here is the code inserted in ser.cfg: if (is_method("REGISTER")) { avp_printf("i:20","$hdr(CSeq)"); xlog("L_INFO"," +*+ 1 : '$avp(i:20)'\n"); avp_subst("i:20","/(.*) REGISTER/\1/"); xlog("L_INFO"," +*+ 2 : '$avp(i:20)'\n"); avp_op("i:20","add/i:0x1100100"); xlog("L_INFO"," +*+ 3 : '$avp(i:20)'\n"); } And here is the log: 3(19936) +*+ 1 : '6543 REGISTER' 3(19936) +*+ 2 : '6543' 3(19936) +*+ 3 : '6543' So the final result is 6543 instead of 6643... Can anybody tell me what I am doing wrong? Thanks in advance. Best Regards, Xavier.