You have requested a single security group:
Dim allGroups As GroupInfo = BRApi.Security.Admin.GetGroup(si, "QA_Admin")So the error is saying that you are treating the return allGroups as a collection ie you think it contains List(Of GroupInfo) when it is a single GroupInfo. Get rid of the For loop. And as sameburn says MessageBox is not valid - use api.LogMessage for Finance BRs. And you then will be checking the name like this:
If allGroups.Member.Name.StartsWith("QA_") ThenThe message is a bit pointless though except to confirm that the security group QA_Admin exists. If you want all the security groups you want something like this:
Dim allGroups As List(Of Group) = BRApi.Security.Admin.GetGroups(si)Note the return is a list of Group not GroupInfo.