Ensure that the field names are short with no spaces
ensure that the fields contain the same data type... just because a number looks like a number, it may not be... confirm this in the originating software.
you have covered no blank rows, no missing entries (substitute some value like -9999 for numeric fields)
If that isn't working, bring the file into excel and confirm the above there, then use the excel to table tool
ps... one missing comma can screw everything up as well