Weird Thumbnail appears beside selection on dropdown list When using Valid if

[Hani_Ibrahim]

when i use Valid if to limit my drop list to certain values i found the icon shown in the photo

However, i used the ref type with other dropdown list without any valid if statement, and it works perfectly.

The Expression used in the valid if part is :

Blockquote

SELECT(SUBMITAL NO[Submittal No],
AND(
[Project_id]=[_THISROW].[Project],
[Submittal Type]=[_THISROW].[Submittal Type],
[Discipline]=[_THISROW].[Discipline]
)
)

as shown in the photo:

Am i doing any thing wrong? how to get rid of that icon?