Error 26597 when using web_add_header

Hello,

I have a script that does the following:

	web_add_header("X-CSRF-Token", "Fetch");
	web_reg_save_param_ex("paramName=TOKEN", SEARCH_FILTERS, "Scope=Headers", "HeaderNames=x-csrf-token", LAST);
	web_url("csrftoken", 
		"URL=http://myurl/session/csrftoken?_={TIMESTAMP}", 
		"Resource=1", 
		"RecContentType=application/json", 
		"Referer=http://myotherurl", 
		"Snapshot=t99.inf", 
		LAST);
	lr_log_message(lr_eval_string("token: {TOKEN}"));
	web_add_header("X-CSRF-Token", "{TOKEN}");

 which fails with the following log:

Action.c(860): web_add_header("X-CSRF-Token") started [MsgId: MMSG-26355]
Action.c(860): web_add_header("X-CSRF-Token") was successful [MsgId: MMSG-26392]
Action.c(861): web_reg_save_param_ex started [MsgId: MMSG-26355]
Action.c(861): Registering web_reg_save_param_ex was successful [MsgId: MMSG-26390]
Action.c(863): web_url("csrftoken") started [MsgId: MMSG-26355]
Action.c(863): web_url("csrftoken") was successful, 60 body bytes, 305 header bytes [MsgId: MMSG-26386]
token: 17CE4F545080354C892893B7DB32EC71
Action.c(873): web_add_header("X-CSRF-Token") started [MsgId: MMSG-26355]
Action.c(873): Error -26597: Added header value is NULL, empty or contains white spaces only. It is added anyway [MsgId: MERR-26597]
Action.c(873): web_add_header("X-CSRF-Token") highest severity level was "ERROR" [MsgId: MMSG-26391]

Any idea how LR can know a parameter on one line, and then forget it by the very next line?

Thanks,

Paul