Perhaps you Exported the 'entire' blouse and not Just the sleeves (1 right and 1 left)? The P4 long sleeve blouse is like a charater and each part (ie. left shoulder, right shoulder, neck, chest, etc) have to be treated separately. Or, did you Add any vertices to it? use the new knife tool in ver8.5? As you can NOT add any verticals if you wish it to be a morph or you will get this error. The only two possibilities I can think of: 1) you exported too much and need to do the parts individualy. 2) somehow you added verticles to the morph.