a!iconIndicator("REMOVE") is not returning particular image.

I am using following code to display icon but somehow this code is working intermittently for different icons,

For Ex: If I chose to return "REMOVE" icon then not able to render image  

a!imageField(

label:"Remove",
labelPosition: "ADJACENT",
size: "ICON",
images: a!documentImage(
document: a!iconIndicator(
icon:"REMOVE"
),
altText: "Remove",
caption: "Remove"
)
)

If I choose to return "ADD" icon then able to render image.

a!imageField(

label:"ADD",
labelPosition: "ADJACENT",
size: "ICON",
images: a!documentImage(
document: a!iconIndicator(
icon:"ADD"
),
altText: "ADD",
caption: "ADD"
)
)

Thanks in advance.