DTW UoM Prices - price in primary currency is not defined

SBO Version: 9.1 PL04

We are trying to perform an import of UoM Prices into a test company but encounter the following error message through DTW:

I have ensured that the correct UoMEntry number if populated in my ITM9 - template from the OUOM table. The correct BaseUom number from the OUGP table is correlates. Despite this, I still receive the above error.

Has anyone else been able to successfully import in UoM Prices?

Thanks,

Sarah