can't handle the template parameters

if i deliver some parameters into a template, and this template uses these parameters as property values. This dones't work.

for example:

template:foo

{{#declare:property1={{{arg1}}}
|property2={{{arg2}}}
}}

[[property3::{{{arg3}}}]]

{{#set:property4={{{arg4}}} }}

page "sandbox" using this template

{{foo|arg1=one|arg2=two|arg3=three|arg4=four}}

and when i "special:browse" this page "sandbox"

i can only find the property3 and property4,which means declare is not functional.

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