Board Thread:Support Requests - Getting Technical/@comment-1824272-20150523151229/@comment-452-20150523165622

The problem is that it's trying to evaluate an empty parameter.

For example: {{#ifexpr: {{formatnum:{{{cost1|1}}}|R}} = 0 Although you've set the default value of "1", the presence of |cost1= means  {{{cost1|1}}}  evaluates to blank, so you get {{#ifexpr: = 0 which causes an error.

Removing the = in the template usage means that the blank cost1 value isn't passed to the template, so "1" is used.

One way to fix it is to replace  {{{cost1|1}}}  with  {{#if:{{{cost1|}}}|{{{cost1|}}}|1}} , which is admittedly a little long.

Another way is to use {{#ifexpr: ({{formatnum:{{{cost1|1}}}|R}}+0) = 0 which evaluates to {{#ifexpr: (+0) = 0 which works. (edit: It also works without the brackets)