Hi there.

I just got touch with Salestouch since last week.

I have created two custom objects calles purchase record and purchase item. Purchase Reocrd is the parent in the master detail relationship with purchase item, and contact is the parent of purchase record.

The thing I want to do is to create a custom field in contact, so that I can calculate the total purchase amount in past 6 months for each contact.

The roll up field let me to sum up, but it only can calculate on specific date, not dynamic/relative date.

The formula field cannot sum, but can use TODAY() function.

When I asked others for suggestion, I was told that I can use Apex to doing this.

However, in the developer console, when I click File>>new, the Apex class and trigger is turned to grey, so I cannot create a new one.

I searched on the internet and someone said that is because of the production org. So I create a new sandbox, but still cannot create a new apex class.

There is another reason, which is about permission. They said the Author Apex field have to be enabled. However, I cannot find this field and I enable a field called Apex REST Services in the permission set. But this one can only be enable in the profile created by me.

I have stuck in this problem for whole day. Could anyone help?

One more additional information, I am using the developer account with free trial. I don't know whether this is the reason.