Don't mean to piss in yer porridge, but hope you bolted the iso rails to your oil pan or a like jig, before you welded the cross brace to them.
If you didn't, all the stars and planets have to be lined up perfectly or your bolt holes will not align with the pan, and/or the brace might interfere with the pan sump.
You'd not be the first to have that happen.
Best of luck!!
