The issue is not with the time dimension. The error says that the mapping you made to the line items is wrong.
Based on the mapping, the system will read each value in the 'Volume' column and try to map it with the line items present in the target modules. Fr ex, Anaplan try to find a line item with the name 58.87728739 as per 1st record. But this should be the case.
My understanding is, you are trying to import the volume data at Acct, SKU and Weekly level. Please do the mapping correctly.
If there is only one data that needs to be imported, then make use of the option 'Fixed Line item' else 'Column header' as per @Misbah post.
To help, please find below,
Column 3: Week
Column 1: SKU
Account Flat list
Column 2: Account
SKU Flat list
Fixed line item
Dat03 history volumes line item
Data Values from
Column 4: Volume
And finally in the line items tab (last tab), mark the destination line item.
I hope you understand!! Let me know in case of any concerns.
I can understand how this issue can be frustrating.
For your Source, if you have
"Week" => to Time
"SKU" => to SKU Flat
"Account" => to Account Flat
Fixed line Item => to DAT03
You are good.
It is when you are under the "Time" tab that the issue may arise.
You need to select the Match names option in the "How to map the source data into the timescale" section. This is because Anaplan is reading Week 1 FY19, Week 2 FY19, and so on as specific names not as units of time.