Why does this numeric compare fail in MDX?

Given the MDX query below you can see that under certain circumstances MDX fails to see the .22 is not less than .22; what's going on here?

WITH

MEMBER Measures.X1as

 1.0 + ((22.0 - 100.0)/100.0),FORMAT_STRING = '.00'

MEMBER Measures.Y1as

 IIF(Measures.X1 < .22,'Fail', 'Pass')

MEMBER Measures.X2as

 (22.0/100.0),FORMAT_STRING = '.00'

MEMBER Measures.Y2as

 IIF(Measures.X2 < .22,'Fail', 'Pass')

MEMBER Measures.X3as

  StrToValue(1.0 + ((22.0 - 100.0)/100.0)),FORMAT_STRING = '.00'

MEMBER Measures.Y3as

 IIF(Measures.X3 < .22,'Fail', 'Pass')

MEMBER Measures.Zas

 IIF(.22 < .22,'Fail', 'Pass')

SELECT{[Measures].[X1],

      [Measures].[Y1],

      [Measures].[X2],

      [Measures].[Y2],

      [Measures].[X3],

      [Measures].[Y3],

      [Measures].[Z]} ON 0

  FROM [APM]

Thanks,

David Skelton