Call Forward Ring Time problem

In FreePBX 2.9.0.2 we setup extension 3001 with call forward to extension 3000. When dialed, CF is not working. The problem comes from:
[May 17 15:06:54] VERBOSE[27526] pbx.c: – Executing [[email protected]:3] ExecIf(“IAX2/astVarna-2906”, “0?Set(ARG1=0)”) in new stack
Corresponding line is:
exten => cf,n,ExecIf($["${DB(AMPUSER/${DEXTEN}/cfringtimer)}" != “0” & “${DB(AMPUSER/${DEXTEN}/cfringtimer)}” != “”]?Set(ARG1=${IF($["${DB(AMPUSER/${DEXTEN}/cfringtimer)}"="-1"]? : ${DB(AMPUSER/${DEXTEN}/cfringtimer)})}))
There is a check if it is != “0” but it doesn’t work for some reason.

As a workaround I configured “Call Forward Ring Time” to be “Always” instead of “Default” and received:
[May 17 15:15:59] VERBOSE[27996] pbx.c: – Executing [[email protected]:3] ExecIf(“IAX2/astVarna-8121”, “1?Set(ARG1=)”) in new stack

[May 17 15:06:54] VERBOSE[27526] pbx.c: – Executing [[email protected]:26] GosubIf(“IAX2/astVarna-2906”, “0?dstring,1:dlocal,1”) in new stack
[May 17 15:06:54] WARNING[27526] ast_expr2.fl: ast_yyerror(): syntax error: syntax error, unexpected ‘’, expecting $end; Input:
[May 17 15:06:54] WARNING[27526] ast_expr2.fl: If you have questions, please refer to doc/tex/channelvariables.tex.
[May 17 15:06:54] WARNING[27526] func_logic.c: Syntax IF(?[][:]) (expr must be non-null, and either or must be non-null)
[May 17 15:06:54] WARNING[27526] func_logic.c: In this case, =’’, =‘3000’, and =‘Local/[email protected]/n’
[May 17 15:06:54] VERBOSE[27526] pbx.c: – Executing [[email protected]:1] Set(“IAX2/astVarna-2906”, “DSTRING=”) in new stack
[May 17 15:06:54] WARNING[27526] ast_expr2.fl: ast_yyerror(): syntax error: syntax error, unexpected ‘’, expecting $end; Input:
[May 17 15:06:54] WARNING[27526] ast_expr2.fl: If you have questions, please refer to doc/tex/channelvariables.tex.
[May 17 15:06:54] WARNING[27526] func_logic.c: Syntax IF(?[][:]) (expr must be non-null, and either or must be non-null)
[May 17 15:06:54] WARNING[27526] func_logic.c: In this case, =’’, =‘1’, and =‘0’
[May 17 15:06:54] VERBOSE[27526] pbx.c: – Executing [[email protected]:2] Set(“IAX2/astVarna-2906”, “USEGOTO=”) in new stack
[May 17 15:06:54] VERBOSE[27526] pbx.c: – Executing [[email protected]:3] Return(“IAX2/astVarna-2906”, “”) in new stack