[Genome] Affy U133 probe mappings missing?

[John Major]

I'm working with U133A Affy chips, and would like to use the UCSC known 
gene mappings for each probe name.

I am using the hg17 assembly, and noticed that a probe was missing(and 
possibly more) from the knownToU133 table (But,  it is listed in the 
AffyU133 table?). 
Probe 117_at maps to HSPA6, and is in both tables above. The probe  
213418_at should also map to that same gene, but is only listed in the 
u133 table above and not in the known gene mapping table?

Were probes that were excluded from the knownToU133 table excluded b/c 
they did not actually align to the gene?

Thanks,
John