validation on multipart form not working

I have same identical problem with the same extension (PAU)
My solution (ASP Classic and VBScript):

Validation toolkit:
.........................
if (cStr(UploadFormRequest("Submit")) <> "") then
WAFV_Redirect = "mypage.asp"
Session("WAVT_COOPcompleta_Errors") = ""
if (WAFV_Redirect = "") then
WAFV_Redirect = cStr(Request.ServerVariables("SCRIPT_NAME"))
end if
WAFV_Errors = ""
WAFV_Errors = WAFV_Errors & WAValidateRQ(cStr(UploadFormRequest("textfield1")) & "",false,1)
WAFV_Errors = WAFV_Errors & WAValidateRQ(cStr(UploadFormRequest("textfield2")) & "",true,2)

if (WAFV_Errors<> "") then
PostResult WAFV_Redirect,WAFV_Errors,"mypage"
end if
end if
...............

for to fill the form with imputed data i use the sessions:
..........
if (cStr(UploadFormRequest("Submit")) <> "") then
Session("text1")=UploadFormRequest("textfield1")
Session("text2")=UploadFormRequest("textfield2")
end if
...........

Regards
Luca