Compilation errors after applying patch 9873923

I have just applied patch 14254641 onto an eBusiness 12.1.3 environment, but it failed with the error message:-

The following Oracle Forms objects did not generate successfully:

au      resource        INVLTENT.pll
au      resource        INVMTXFH.pll

An error occurred while generating Oracle Forms objects.
Continue as if it were successful [No] :

I found a very similar hit to this one in Note 1216143.1, which recommends the application of patch 9873923:R12.INV.B 
As the versions of these two files we were on were lower than the versions in this patch, I applied the patch.

However, when I apply the above patch, I now get the error message:-