conditional formating excel VSTO

Question

I get this error as not sure how to access the method/functions for conditional formatting
I am using excel.range for this line under a with clause
.IconSetCondition.IconSet.IconSets = "xl3Triangles"

System.MissingMemberException
HResult=0x80131512
Message=Public member 'IconSetCondition' on type 'Range' not found.
Source=<Cannot evaluate the exception source>
StackTrace:
<Cannot evaluate the exception stack trace>