FCC application - Assign UDA using Groovy

I realized its "planning" forum, however i am not able to delete this FCC related question.

Summary:

In FCC application, I am trying to write a groovy script to assign a UDA to an account member, but its failing at saveMember() saying its not allowed.

Do we have some restriction in FCC?

Code Snippet
Cube cube = operation.application.getCube("Consol")
Dimension dimAccount = operation.application.getDimension("Account", cube)
Member mbrAcc = dimAccount.getMember("1301011")
Map<String, Object> mbrMap = mbrAcc.toMap()
println mbrMap
mbrMap["UDA"] = "PPE"
println mbrMap
dimAccount.saveMember(mbrMap)

ERROR
A validation error was received from the Planning server.
'Error:The Groovy script failed to compile with internal error: Compile Error: