RDLC Report in Asp.Net

Question

I have created Rdlc report in Asp.Net using vs2005,how do I change the sign for negative values,if value is negative I want to remove negative sign and make its font color red and green if it is positive.

 

I have written the following expression for it,

 

=IIf(Fields!Amount.Value>0,"Green","Red") it is just changing the color of text how i should I remove negative sign.Please do let me know about it.