Use the parameters in the "lr_save_param_regexp" function

The next case is found result:

char *html = "<title>Any Title</title>";
lr_save_param_regexp(
        html,
        strlen(html),
        "Ordinal=1",
        "RegExp=<title>(.+)</title>",
        "ResultParam=reMatchesParam",
        LAST
    );

But this case any results is not being found:

    char *html = "<title>Any Title</title>";
    char *bound1 = "<title>";
    char *bound2 = "</title>";
    
lr_param_sprintf ("SEARCH_PREPARED_MASK", "%s(.+)%s", bound1, bound2);

lr_error_message("%s",  lr_eval_string("{SEARCH_PREPARED_MASK}"));  // output: "<title>(.+)</title>"
    
lr_save_param_regexp(
        html,
        strlen(html),
        "Ordinal=1",
        "RegExp={SEARCH_PREPARED_MASK}",
        "ResultParam=reMatchesParam",
        LAST
    );

The "SEARCH_PREPARED_MASK" parameter is not replaced in the RegExp part.

Could tell me please why?